I have a problem with my prints having a small separation gap between layers when I have a corner and the Z layer ends or starts for a partial distance. The gap reminds me of a gap between a print and its raft. Usually 1 layer just seems to be missing in places.
I've been printing about a year now and I've tried different temps, line width, layer thicknesses. The problem has even been a problem after installing new firmware. I use Cura V4.5.0 and an Ender 3 printer. The problem is rather difficult to describe so I've attached an image demonstrating the problem.