Not to my knowledge. I haven’t seen any communication on the dev mailing list on this and there is nothing in the IPFire bugzilla.
I don’t use this option on my production IPFire or on my vm testbed systems so have no personal experience of what you have found.
unbound was updated from 1.13.1 to 1.13.2 in Core Update 162 and its changelog info mentions dnssec a few times but I don’t have enough knowledge to tell if this might have caused the problem or not.
Probably worth raising as a bug in the IPFire bugzilla and providing your log info of the problem.