Were you getting caught in application startup loops where it would never make any progress in processing any blocks? Trying to figure out if we're running into similar issues.

That one was fixed by upgrading to 0.19.0-beta

Another one was some random remote BTC node going offline and my network connection to it timed out, then my server would gracefully shut down. It looked like an unexpected exception that was being caught, and shutdown is how it was handled.

When I switched the .service file to always restart instead of only on failure, the wallet would be locked. After manually unlocking it, it'd run into an issue, reboot, and start over from the beginning... only to repeat this process.

I hacked around this by turning up the log level to debug and it never happened again. It's been a lot of things like this, where no cause is ever identified and nobody understands why the weird workarounds evade the core problems.