possibly..... maybe you accidentally ended up with a section with the same name as another section (it amazing YR doesnt explode with the VIRUS infantry using the VIRUS warhead). That normally can produce all sorts of unwanted stuff.
No, I don't think it's that, I checked Rulesmd.ini & Artmd.ini with Section Edit.
I will make a SHP with a crashing ZEP and I will give to [ZEP] Crashable=no and as the Explosion= this animation, and I hope it will work...
And I won't add any new building ( after all, I already have too many... )