Synch stops with an error: it cannot get a lock over certain item.
Sometimes it appears in iOS app, sometimes in desktop app.
The workaround is the same: open the other app (the one without issue) and click in another note or anything else, much better if selecting a different notebook and wait for both synch proesses to finish. Normally (99% of cases) this will solve the issue. When not, simply repeat the process. At second or third time, it will work, simply because the synch periodical timing.
A.- be selective on what actions cause the lock (i.e. editing) because not all actions should lock the item. So, this can reduce the locking issues to a minimum.
B.- by timeout: if there is no action in the locked item / app (i.e. click, type, edit, etc.) for a while (i.e. 1 minute), simply left and clear the lock automatically.
(I'm supposing the lock is made in items, not in a single entity that controls the whole sync process)
The next version of the iOS app (13.1.x, which should be available soon!) has an option to disable sync locks. When released, it should become possible to disable sync locks from configuration > synchronization > advanced > sync locks:
