After upgrading to f/w v 3.9.9.8_BT, my IP bind list has dissapeared and i can now only add 10 entries.
Is there a way to fix this annoying issue???

I'm seeing the similar behaviour on two 2862 routers. In both cases, when a new bind entry is added the list truncates to 12 (not 10) entries. In one case this selectively removes all entries for subnets other than for LAN 1. The other router has only one subnet defined but still truncates, losing entries above 12. I have tried this several times.
Very annoying. Please fix this new bug.

Additionally, if I try to restore a recently saved Bind List file this popup warning appears:
"Config filename does not match, please check!"
and I think the restore does not happen.

I downgraded my firmware by several versions. I can now add more devices to the bind list but ALL my bindings from almost 20 years of Draytek ownership have been wiped and i'm not particularly chuffed about them vanishing into the ether. Draytek, FIX THIS BUG!!!

If you have a full configuration backup from System Maintenance then this includes the Bind List. Surely you have one of these from before installing 3.9.9.8_BT.

No, i don't because i never considered the fact that this would happen (please spare me the lecture on backing up).My 32TB NAS is backed up, not a 1k CSV file. ALso, i only flash with the version that doesn't factory reset the router. That and that i've upgraded literally thousands of Draytek devices and never encountered this. So no. I don't have a bind list back up....