Creatures Caves

I'm doing a wolfling run with two separate populations (norns & ettins) and noticed that a number of eggs were autokilled. I turned autokill off, created a new world and started injecting the killed genomes, and got this error on multiple hatches:

Runtime error in agent 3 4 1 (Norn egg) script 3 4 1 9 unique id 564387
Invalid gene variable
... 1020 attr va03 lock {@}newc 4 targ 1 ov01 0 accg game ...

Note that on several occasions I've managed to reinject the same genome and it's worked fine, so it's not some wonky gene doing it. Any ideas on how to solve this? I can't very well do a wolfling run if my eggs sometimes fail to hatch!

By the way, I don't care if anyone steals my ideas for their own work, as long as you don't try to stop me from making my own stuff. Many ideas I mention are things I don't have the time or skill to actually do.