I’m going to add some new discoveries about the problem with the grid I mentioned before.
I must say that I’m using a file created initially with ConDoc 5.1 (before 5.2 upgrade) and Sketchup 2021. The grid appears on the Line Drawing 00 style and viewports rendered as hybrid. When I change them manually to vector, everything looks ok. What I’m curious about is the fact that the grid appears on the objects assigned to a layer that is not visible in this viewport.
Any ideas what might be causing this behavior?