Is this a bug, or is it supposed to take forever to start the lighting build process?

So I am doing a test, but when I want to build the lighting, it takes WAY to long to even start the process with the Building Agents.

As you can see in the image, there are not many objects / actors in the map / level. Is there a reason why it is taking this long?
This is in 4.21 and 4.22. I don’t know why this is happening, but does some else know about this, and/or have a solution for this?

Thanks in advance!