level editor viewport navigation gets stuck

Hello, when navigating in the level editor viewport utilizing Maya style mouse navigation (holding ALT, left / middle / right mouse button), I am randomly running into situations where I cannot move further in. The view seems to get stuck at somekind of “invisible wall” and all I get when trying to move in closer is some jittery back and forth. This happens at random places in the level and always at different spots and can be temporarily resolved by selecting an object and hitting F to focus. However since it happens quite often, I was wondering if there is a better solution to this or if I have to turn something on / off … Thanks!