R-26... Why no screenshot xD
I mentioned this before: Please provide screenshots or additional info where relevant. Also you provided a seed but no version number. Seeds are different every version (and this also matters for future reference), so it helps to follow the bug reporting instructions. I did manage to find it, though it's very helpful to have this extra info.
Anyway, yeah that particular T/Q checkpoint prefab does sometimes act sorta weird, surprisingly in this case it managed to be placed without an opening to rest of the map, which was blocked. Very rare apparently, but good to have a test case for fixing this particular prefab (which is quite different from others).