While in my previous experience, sync issues were seemingly related with having a second instance open, in recent days, I have the issue that syncing works only occasionally, even when only on one device. More often than not, changed cards show an infinite 3-dots-animation after saving. Interestingly, the sync indicator in settings says “connected”, not mentioning pending changes.
Logging of and on again leads to loss of data, or, sometimes, weird blends of old and new state of markup content.
Somehow I got the feeling that it is not really a connection thing but an issue with diffing/merging consecutive versions, might even be related to my other issue.