Some Nikkor LTM lenses (for example 35/2.5 and 28/3.5) do not work properly on newer Leicas unless you change the frameline lever (M4p and M6 in my case). Not sure how wide the M8 frameline lever is, but I wouldn't discard that it can happen there, too.
OP, let us know which lenses you are talking about and which LTM adapter you are using. Then we can help.
Roland.