Just toggle the mods off, wait for the enemy to return, then toggle back on.... Repeat as necessary during any level.
This is a known issue by the modder, I believe. Some of the mods don't work on some of the levels. Good luck!
Hi JokerArt,
The rocks cannot be mined now. They turn invincible instead of breaking in one hit. This makes it impossible to proceed through the game. When you are able to, can you please fix this.