^ This issue arises from a detail of DOS workings that Lemmix did not accurately reproduce back when it was the main platform for custom content (which is also when the PSP remakes were originally created). In short, DOS physics require that object trigger areas have coordinates and sizes that are divisible by 4; and Lemmix restricted object X coordinates to multiples of 4 accordingly. However - what it should have been doing, and what my later builds of Lemmix are doing, is restricting object coordinates to multiples of 8. This is what DOS Lemmings actually does, for graphics-related reasons*, and since Lemmix's intent is to accurately replicate DOS, that's what I made it do here too. (For the record, object Y coordinates are not restricted. However, physics wise, the trigger area is moved up to the nearest multiple of 4 on the Y axis - which is a major cause of the "exit doesn't work unless buried slightly in terrain" issue often seen in DOS / Lemmix levels.)
* disclaimer: I don't know for sure that it's for graphics-related reasons, but it's highly probable based on various factors I do know about the DOS games.