more details from the log if it helps?
edited just to show anything relating to “cast” or “media_player”
[32m2018-01-09 18:18:01 INFO (MainThread) [homeassistant.loader] Loaded media_player from homeassistant.components.media_player[0m
[32m2018-01-09 18:18:01 INFO (MainThread) [homeassistant.loader] Loaded media_player.cast from homeassistant.components.media_player.cast[0m
[32m2018-01-09 18:18:01 INFO (MainThread) [homeassistant.loader] Loaded discovery from homeassistant.components.discovery[0m
...
[32m2018-01-09 18:18:01 INFO (MainThread) [homeassistant.setup] Setting up media_player[0m
...
[32m2018-01-09 18:18:01 INFO (MainThread) [homeassistant.components.media_player] Setting up media_player.cast[0m
...
[33m2018-01-09 18:18:11 WARNING (MainThread) [homeassistant.setup] Setup of media_player is taking over 10 seconds.[0m
[33m2018-01-09 18:18:11 WARNING (MainThread) [homeassistant.components.media_player] Setup of platform cast is taking over 10 seconds.[0m
[31m2018-01-09 18:18:25 ERROR (SyncWorker_4) [pychromecast.socket_client] Failed to connect, retrying in 5.0s[0m
[31m2018-01-09 18:19:01 ERROR (MainThread) [homeassistant.components.media_player] Setup of platform cast is taking longer than 60 seconds. Startup will proceed without waiting any longer.[0m
[32m2018-01-09 18:19:01 INFO (MainThread) [homeassistant.core] Bus:Handling <Event service_registered[L]: domain=media_player, service=turn_on>[0m
[32m2018-01-09 18:19:01 INFO (MainThread) [homeassistant.core] Bus:Handling <Event service_registered[L]: domain=media_player, service=turn_off>[0m
[32m2018-01-09 18:19:01 INFO (MainThread) [homeassistant.core] Bus:Handling <Event service_registered[L]: domain=media_player, service=toggle>[0m
[32m2018-01-09 18:19:01 INFO (MainThread) [homeassistant.core] Bus:Handling <Event service_registered[L]: domain=media_player, service=volume_up>[0m
[32m2018-01-09 18:19:01 INFO (MainThread) [homeassistant.core] Bus:Handling <Event service_registered[L]: domain=media_player, service=volume_down>[0m
[32m2018-01-09 18:19:01 INFO (MainThread) [homeassistant.core] Bus:Handling <Event service_registered[L]: domain=media_player, service=media_play_pause>[0m
[32m2018-01-09 18:19:01 INFO (MainThread) [homeassistant.core] Bus:Handling <Event service_registered[L]: domain=media_player, service=media_play>[0m
[32m2018-01-09 18:19:01 INFO (MainThread) [homeassistant.core] Bus:Handling <Event service_registered[L]: domain=media_player, service=media_pause>[0m
[32m2018-01-09 18:19:01 INFO (MainThread) [homeassistant.core] Bus:Handling <Event service_registered[L]: domain=media_player, service=media_stop>[0m
[32m2018-01-09 18:19:01 INFO (MainThread) [homeassistant.core] Bus:Handling <Event service_registered[L]: domain=media_player, service=media_next_track>[0m
[32m2018-01-09 18:19:01 INFO (MainThread) [homeassistant.core] Bus:Handling <Event service_registered[L]: domain=media_player, service=media_previous_track>[0m
[32m2018-01-09 18:19:01 INFO (MainThread) [homeassistant.core] Bus:Handling <Event service_registered[L]: domain=media_player, service=clear_playlist>[0m
[32m2018-01-09 18:19:01 INFO (MainThread) [homeassistant.core] Bus:Handling <Event service_registered[L]: domain=media_player, service=volume_set>[0m
[32m2018-01-09 18:19:01 INFO (MainThread) [homeassistant.core] Bus:Handling <Event service_registered[L]: domain=media_player, service=volume_mute>[0m
[32m2018-01-09 18:19:01 INFO (MainThread) [homeassistant.core] Bus:Handling <Event service_registered[L]: domain=media_player, service=media_seek>[0m
[32m2018-01-09 18:19:01 INFO (MainThread) [homeassistant.core] Bus:Handling <Event service_registered[L]: domain=media_player, service=select_source>[0m
[32m2018-01-09 18:19:01 INFO (MainThread) [homeassistant.core] Bus:Handling <Event service_registered[L]: domain=media_player, service=play_media>[0m
[32m2018-01-09 18:19:01 INFO (MainThread) [homeassistant.core] Bus:Handling <Event service_registered[L]: domain=media_player, service=shuffle_set>[0m
[32m2018-01-09 18:19:01 INFO (MainThread) [homeassistant.setup] Setup of domain media_player took 60.4 seconds.[0m
[32m2018-01-09 18:19:01 INFO (MainThread) [homeassistant.core] Bus:Handling <Event component_loaded[L]: component=media_player>[0m
...
[32m2018-01-09 18:19:13 INFO (MainThread) [homeassistant.components.discovery] Found new service: google_cast {'host': '192.168.0.123', 'port': 8009, 'hostname': 'e83a6f70-0eEDITED-678c20f108cd.local.', 'properties': {'id': 'e83a6f700eEDITED894678c20f108cd', 'cd': '23302EC23F8AEDITED01C74E4E5', 'rm': '793A617F7E741FED', 've': '05', 'md': 'Google Home', 'ic': '/setup/icon.png', 'fn': 'Lounge speaker', 'ca': '2052', 'st': '0', 'bs': 'FA8FCA32444A', 'nf': '1', 'rs': False}}[0m
[32m2018-01-09 18:19:13 INFO (MainThread) [homeassistant.core] Bus:Handling <Event platform_discovered[L]: service=load_platform.media_player, platform=cast, discovered=host=192.168.0.123, port=8009, hostname=e83a6f70-0e6EDITED4-678c20f108cd.local., properties=id=e83a6f700e6EDITED0f108cd, cd=23302EC2EDITEDAE01C74E4E5, rm=793A617F7E741FED, ve=05, md=Google Home, ic=/setup/icon.png, fn=Lounge speaker, ca=2052, st=0, bs=FA8FCA32444A, nf=1, rs=False>[0m
[32m2018-01-09 18:19:13 INFO (MainThread) [homeassistant.components.discovery] Found new service: google_cast {'host': '192.168.0.99', 'port': 8009, 'hostname': '192-168-0-99.local.', 'properties': {'id': '09d5436a71494d918e38a30c44421eae', 'ic': '/setup/icon.png', 'ca': '5', 'md': 'CastReceiver1', 've': '04', 'rrv': '1.01', 'st': '0', 'rmodel': 'CastReceiver1,1', 'fn': 'M8S-99', 'rsv': '1.00'}}[0m
...
[32m2018-01-09 18:19:13 INFO (MainThread) [homeassistant.components.media_player] Setting up media_player.cast[0m
[32m2018-01-09 18:19:13 INFO (MainThread) [homeassistant.components.media_player] Setting up media_player.cast[0m
[32m2018-01-09 18:19:18 INFO (SyncWorker_7) [pychromecast] Querying device status[0m
[32m2018-01-09 18:19:18 INFO (SyncWorker_0) [pychromecast] Querying device status[0m
[32m2018-01-09 18:19:18 INFO (SyncWorker_7) [pychromecast] Querying device status[0m
[32m2018-01-09 18:19:18 INFO (SyncWorker_0) [pychromecast] Querying device status[0m
[33m2018-01-09 18:19:23 WARNING (MainThread) [homeassistant.components.media_player] Setup of platform cast is taking over 10 seconds.[0m
[33m2018-01-09 18:19:23 WARNING (MainThread) [homeassistant.components.media_player] Setup of platform cast is taking over 10 seconds.[0m
...
[31m2018-01-09 18:19:37 ERROR (SyncWorker_7) [pychromecast.socket_client] Failed to connect, retrying in 5.0s[0m