The "overlap" mode behaves as intended, by the way. It is intended to be used when exporting stems that are then used as individual MIDI tracks in the DAW where they are imported. The rationale is to be able to export more than 16 concurrently playing instruments for this usage mode.

The default mode, however, should behave as most people would imagine and as if all instruments were exported into a single MIDI track. I have now managed to reproduce your issue with the pitch bend based on the description, so there is no more need to upload an example file (you can simply zip or 7z your modules to attach them, by the way).

r11292 should fix this problem. You can download a test build from here: https://builds.openmpt.org/builds/auto/openmpt/bin.win32/1.28/ (32-bit) or https://builds.openmpt.org/builds/auto/openmpt/bin.win64/1.28/ (64-bit) - it will be available in a few hours at the latest.

r11292 is now downloadable from the links above.

I have found another small issue when instruments with differing MIDI pitch wheel depth would share the same channel (only a concern when exporting a track that was using instrument plugins, otherwise all instruments use a pitch wheel depth of 12); this will be corrected in the next release.