summary : it's known that when we lagged, some creeps from enemy base will appear as our ally creeps, both health bar and model, but somehow the game takes that enemy creep also an ally creep (and vice versa)

how to repro :
lag your game using any means (i got around 3000 ms, no idea what happened), can be done even in practice lobby
use any hero with Unit targeting skill (was using Storm Spirit and using his Electric Vortex)

actual result :
if enemy creeps converted to ally creeps:
'Ability can't target allies' (really..? i can right-click and hit it just fine, my creeps can even hit it just fine)

if ally creeps converted to enemy creeps:
you can cast Unit targeted abilities, but when it is going to reach Cast Point (or something), the warning 'Ability can't target allies' will show up

expected result :
the bug is visual, and any ability should work normally without those warning