Because events were missing in Loc_ai\LAi_fightparams.c. If you compare the current 2016 version from Itch to the 2021 version, you will see a bunch of code for event_handlers added, even with a comment "//Boyer add below" which is my last name.
I made the change for you and uploaded to that same MEGA link, just the LAi_fightparams.c file by itself.
....please don't tell me I have to review all the 2021 files...I did the most obvious ones I could think of, but I really don't want to do them all.