Attacks from fighting-types don't hit weakness

I was playing a match with my Mega Lucario ex deck. I had Solrock in active and used Cosmic Beam against their Fezandipiti ex. For some reason, damage calculation did not account for Fezandipiti's 2x weakness to Fighting, and I missed a KO because of the bug. As far as I can tell, Fighting-types are the only ones affected.