This might be related to this depth buffer issue, as it looks like it’s a render state that getting corrupted. I have a number of Technical display mode layout details, and fiddling with one can cause the others to either render correctly or not.
What’s odd is that this state persists back into the perspective editing window… and the only way to clear these mysterious clipping planes is to activate one of my normal clip plane objects in the perspective view which appears to reset the clip plane list.