Strange tempo problem

I installed my system with Debian and recently moved some older renoise files to my HD.

When loading a song it opens with e.g. 120 bpm, reloading it I get 145 bpm and reloading again the tempo is set to 155 bpm. I checked the global settings and Midi clock slave settings is set to none. I have the feeling that I asked a similar question once here, but I don’t find it.

edit: It’s related to JACK Transport sync. When disabling this the bpm stay constant. I wonder where renoise get the (changing) tempo setting from…