Light artifact in actor BP

Hello
I have a problem with project 4.16 after converting to version 4.18
I got strange problems with light like a gradinet on the midle scene but only on BP actors (movable actor)

what I tried

  1. I removed all the light to find the problem, but still nothing
  2. the lightmass is still nothing
  3. I did not get anything wrong with UVW
  4. the material still nothing

please help

I attach a screen

when I move the object to the bottom it’s ok when the problem comes up
something wrong with the light