If you try using unconfigured skills/items, nothing should happen other than the item/skill not having a range at all.
Unconfigured actors/enemies won't have a move range, it would be 1 by default, it may be missing move ai and action AI array setup but otherwise, nothing should truly happen.
Can you tell me exactly when this occurs during the TBS battle? Is it during placement? When battler is moving? When auto battler is acting? When player battler is acting? For skills or items?