Illegal character and operation canceled

I finally managed to get NextCloud installed (did it manually) and upgraded to the latest version. However, the desktop clients are failing with certain files the way that OwnCloud desktop client used to fail years ago, long fixed. Note that these are the same files that were previously synced with OwnCloud. (Forgot mention that the desktop clients are running on OS X machines)

For example, I’m seeing errors such as “Illegal character” and I’m also seeing “Operation canceled”. As far as the latter is concerned, a brief search of the forums suggests that the “Operation canceled” problem was fixed in 2015.

Any help would be much appreciated, I really don’t want to have to go back to OwnCloud

I’ve noted that all the files that failed to sync were sample automated work flows in various Microsoft User Data folders. I removed all the sample workflows and now everything is synced properly.

However, I’d like to understand why those files didn’t sync. I noticed that a few of those filenames had backslashes in them though. But I would have hoped that NextCloud would handle such things