Great to hear 2.0.2 fixes this. I'm a bit lost thinking about a bug fix. We had some since then I guess, and I would have to dig through the log myself.
However, the most obvious would be a zero window where the persist timer doesn't start or somehow doesn't work correctly.
Are you able to reproduce this now? Can you debug it? Would you need help in debugging?
I'm not at my PC very often right now, but I'll see if I find something. Maybe you can dump the PCB in question once it stops plus lwip_stats, that could help finding the issue.