I am running Nextcloud v9.0.1 and the the desktop client v220.127.116.11 on Windows7.
The bug causes the client to enter the RED status with the erorr message from Csync not founding the folder.
To reproduce the problem just create the following folder structure in your local folder:
Then drag a pretty large folder “ccc” from your desktop into “aaa”; when the folder “ccc” icon (I really mean the folder’s icon, not the service icon on the panel) switches from the blue to the green status, that’s means it’s just been detected by the client but not sync’ed yet. At that point I see the service icon switching itself from green to blue, in the attempt to upload the “ccc” folder. If I quickly move the “ccc” folder into “bbb” the client enter the RED status, complaining “CSYNC is not able to find the ccc folder”.
If this is not enough to reproduce the problem I will try to make a quick screencast of what’s going on.