Oh ok, I thought that slowing down was on purpose. Mh, maybe a collider issue that when the walls are activated the enemies collider is in the wall collider already and cannot bounce off from it. Which game engine did you use?
I feel like that could be the issue, They seem to always almost stop if they are IN the wall. I use GamemakerStudio 2
Finally fixed the problem! Thanks for telling me!
Yay! I am glad you found the solution :)