I'm playing as the Sophons with no special settings and it is turn 101. I am able to spend resources on the +20% Infantry Damage Evolution, but after it subtracts the resources from me, the upgrade doesn't register. I can do this multiple times and it keeps taking resources and not applying the evolution. I've tried ending the turn and repeating the process, but I get the same results. However, after loading a previous turn, when I purchased the evolution, it triggered correctly. I'm not sure how to reproduce this but if it pops up again I will update.