As I tell customers who ask, there are problems fitting locks to bedroom doors. For fire safety reasons you can’t fit a regular deadlock, especially if higher than ground floor or windows are barred. A panic lock is often too expensive for “just want to lock my bedroom door”. A rim latch (a “Yale”) is often the best bet*. However, the really cheap Yale can’t be fitted to a hollow door. And most bedrooms in shared occupancy housing have cheap, hollow doors.
That hadn’t stopped this landlord from trying to fit one to this bedroom door, however. I was there to let someone in. They’d lost their only key copy. Before beginning, I pointed out that the third fixing screw was doing anything as there wasn’t any wood behind it. The cylinder was a bit loose and wasn’t flat to the door surface.
First I found that the fitter hadn’t shortened the retaining bolts. Rim cylinders are bolted to the lock, through the door. But they are sold for the thickest of doors and have to be shortened if they are to grip in narrow doors. To overcome the ensuing flopping about of the cylinder, the fitter had vainly tried stuffing paper in. Having corrected all of that, I realized that the fitter had also made the classic mistake of not looking at the instructions and the template and noting that the hole for the cylinder is not coaxial with the centre of the lock. And this sad apology for a fitter hadn’t done what most carpenters sheepishly do when they realize this, which is to fit the cylinder upside-down.
(Which is probably why your cylinder is upside down; if it is.)
* However, unless you’ve been very careful in your choice of the exact model of “Yale”, it will be all to easy for the door to slam shut behind you as you head off to the bathroom, probably without your key about your person.