Shotcut shortening clips automatically

OK so I have just started using Shotcut and i am liking what I am seeing so far but I keep getting a problem when I try to compile various clips into one video in the timeline. For some reason some - not all - the clips get shortened from their original length. It happens entirely randomly to any of the 4-5 clips I am bringing together, but so far has always happened to every video I compiled. It doesn’t seem to matter how long the clip is and when I go back and look at the original, the removed bit is still there. Am I missing something simple please as its so annoying!