My first forum post! I’ve searched and tried to debug this myself for days. I had hoped that updating to 110 today might fix it but no joy.
I have 3 media player cards in the Lovelace UI, 1 of which does not render the artwork of currently playing media. All 3 entities and cards are part of the same entertainment system.
HA set up is as follows:
Hassio running the HassOS image on an Intel-NUC
Issue present in 109 then persisted in todays update to 110
using default theme to avoid any formatting conflicts
Issue Behavior
The Artwork (entity_picture) does not render on my FireTV media player card.
It does render on my Kodi and LG-TV cards.
Furthermore, if I visit the respective URLs in a browser, the FireTV URL downloads an empty file whereas the Kodi URL downloads an image file.
The LG URL actually renders the image in the browser window, though this is often (not always) a blue screen instead of a desired screen cap.
All 3 media cards change in color to reflect what is on screen.
Media Player Cards
- FireTV - androidtv entity
entity_picture: /api/media_player_proxy/media_player.firetv_cube?token=57c82ddc6f5c9e5a89b99ec5f2e80d9e7da85e7578e3f2d43233ce25678a218f&cache=1589986412.366995
- Kodi - side-loaded on the FireTV
entity_picture: /api/media_player_proxy/media_player.eric_s_kodi?token=d47c7a21717b7e077da7363a272e4183cdc66626d4948f532e67b35ee804a89f&cache=d527d2217daee19d
- LG-TV - using the lg-netcast integration and not WebOS
entity_picture: /api/media_player_proxy/media_player.lg_tv?token=c2d80278c348e2b07c973504362e95dce8f1b34c9707fb4dffc51134ab90ad10&cache=fa0d0522417619be
I noticed that the FireTV URL has a “.” in the cache. Wondering how that happens and if that is part of the problem? I’ve looked through my debug logs and couldn’t find anything glaring. I might need to be pointed in the right direction in this department. This all might seem like a minor issue but it’s driving me crazy 
Any help will be greatly appreciated!
Edit:
Screenshot for clarity -
