I've been having this issue on a specific Logic session where I export a midi file with 'export from selection' from a couple of instrument tracks, having activated cycle (loop) and having set the end of the project to 40 (for example)... If I open the exported midi file on Logic everything is fine. But when I open it on Sibelius the project has 2001 bars in total. I've tried all the obvious things, checking midi events, markers, tempo changes, automation, opening a new session in Logic and importing the project again, changing settings in Sibelius, etc.
I think it's a Logic issue, and not Sibelius, because when I open a new project from scratch and export a midi file it works fine. It's worth saying that the problematic session has a movie file, but it continues behaving that way even when the movie file has been deleted, and the audio. To be honest, at this stage I just want to get to the heart of the problem to understand what's happening and prevent it from happening in future projects.
Thanks for your help!!