Out of video memory while saving map as

I am having a very annoying problem here.
Whenever I want to make a new map, I want to use an existing map as kinda template by saving it with a different name.
Unfortunately the editor crashes with the message
Out of memory trying to allocate a rendering resource. …

I don’t understand, how this may is happening.
Attached you find the latest log, renamed to .txt.

I hope, someone can help me.

This seems to happen only for some maps.
If I loaded a different map and tried to save that, it works.
But still: Why does this happen?

My system info might be helpful:

  • AMD Ryzen 7
  • 32GB RAM
  • Geforce RTX2070