Maybe this is one of the relevant log messages:
warning: Error running OnCollisionCheck script in Entity at 27a60700: Unexpected type for army object
stack traceback:
[C]: in function `IsEnemy'
...rogramdata\faforever\gamedata\lua.nx2\lua\shield.lua(360): in function <...rogramdata\faforever\gamedata\lua.nx2\lua\shield.lua:334>