Wood can be unforgiving...
I replaced the hinges to our hall bath with offset ones so my FIL could use it with his walker (it got the door out of the way enough for him to roll in). It turns out that there's apparently a big nail or something from the framing behind the trim in the perfect spot to interfere with one of the longer hinge screws.
I ended up trying to use some plastic hollow-wall anchors to give the screw enough to bite into, but it's still not right (even after putting the "original" hinges back years later).
It's amazing how a "simple" job can be so difficult to do properly...
Good luck!
Cheers,
Scott.