Isometric cuts off what I can see in the Scene View

Hi, I'm a newbie; and I'm having a frustrating problem.

When I'm in perspective mode, my entire Scene View is filled. But when I switch to isometric, chunks of the scene view start getting sliced out of existance. I can't figure out a pattern to the slices, but as I rotate around by dragging alt-left-click things appear and disappear seemingly-randomly. The best description I can think of (of the vanishing) is that it's as if someone is taking a plane that I cannot see through and slicing it across my view; and as I rotate around, the oblivion-like plane moves around too, cutting off my view to various parts of my Scene View.

What's going on?

Thanks in advance.

I’m not sure why that happens, but it’s super annoying.

FIX: select an object, probably a small one, and press “f” in the scene window to focus on it. After that, it should work fine.