Too bad I don’t have a backup from before the condition. I would have done that when I was done.
I would consider this a workaround because you lose the last item configuration. And if it happens again…
Strange that there are no errors in the log when the file is broken.
I had a similar problem with the .json file for the rules.
See here:
[SOLVED] OH3 Issue: unable to create rules, scripts, schedules
But the solution there is no option for > 350 items.