2.3.3_1 upgrade removing blocked IPs in Suricata legacy mode
As far as I can tell that is what happened, is this expected behaviour?
They are supposed to stay blocked for 28 days.
I actually just happened to post a thread on how to keep your snort2c table persistent.
When you updated you had to reboot, anytime you reboot your blocked hosts lists will be flushed.
Just follow the instructions here and you can keep your lists! It's actually really easy.