Cloud Sync fails for one drive (other are OK)

My Data is organised on multiple partitions, all on the same SSD, each with it's own drive letter.
I've set up a SYNC for each drive letter and this works fines except for one drive "S:".
I already removed and recreated the sync for this drive but the problem stays.
It's a rather small drive (1,65GB) and I have more then enough space left on my subscription.
At regular times Acronis tries to sync but fails each time with two error messages in the log file.
When I search for the error code I get a time-out or nothing is found.

First Error line:
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Synchronization has failed.
More information about this error and solutions may be available online in the Acronis Knowledge Base.
To access the online resource manually, enter the event code at: http://kb.acronis.com/errorcode/
Event code: 0x019A005D+0x01ED03E8+0x0191001C+0x00040014+0x0000FFF0+0x80070005

Second Error line:
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Failed to copy changes of synced data from ERQC_DESKTOP to Acronis Cloud: Synchronization has failed. The sync will be restarted automatically later
More information about this error and solutions may be available online in the Acronis Knowledge Base.
To access the online resource manually, enter the event code at: http://kb.acronis.com/errorcode/
Event code: 0x019A0000