MARTELL'S PROFILE

EDIT: Sorry, solved it. Delete, please!

Today I decided to clean up my games "monster" and "monster party" sections by taking out all normal RTP monsters/groups. After that, I copied and pasted all my own monsters higher on the list. Then redoing the monster groups. After adding all the new groups to my game, I tested some system images. I tried them out,
during the test, I decided to try battle-wise. In the end, before the transition-to-battle could even be started, a message popped up saying "invalid monster group". Could anyone explain what I did wrong?

EDIT: The test was in the game, not in the DB. And it was a random encounter.

EDIT 2: Also, this occurred today. And it happens with both the normal version and v187

IMPORTANT UPDATE: Random encounters are working fine on all maps except for one group of maps.