I got the strange behaviour with my HA setup and I simply cannot track the source.
Since the Synology integration has been changed the sensor names changed as well.
I surely changed every sensor name to the correct one reinstalled even the Synology integration itself and everything is working perfectly.
Nevertheless if I check my config it shows the same error as my log:
Log Details (ERROR)
First occurred: 12:54:14 AM (1 occurrences)
Last logged: 12:54:14 AM
Platform error: sensor - Integration ‘synologydsm’ not found.
I do not know where to search for the source of the error. Does anybody have a clue?