Playback Issue

Is there a specific score where this happens, and can you attach it if so? And what system are you using (i.e. your operating system, architecture, which revision of MuseScore)? Are you using the default soundfont (View>Synthesizer)?

See also
#279256: Playback Glitch
#279206: Selecting notes for playback
#279050: Saving during playback causes it to skip to a random note and hang, moves playback cursor elsewhere
#279481: Irregular playback.

You can replicate it on macOS if you are working on an arrangement 76 - 100k or more and make some changes and don't save but start playing the piece it jumps similar to how it does when you press save while playing and it jumps. it is like it is saving the change history ???? The jumping is less btw, happens on larger 76-100k or larger file size. 26k or so it no longer jumps.

There seem to be a lot of these reports that may all be the same!
Not soundfount in my case. I changed back from my own instruments / soundfont to the default Instruments / MuseScore_General combination - I could imaging that the effect might have been slightly different, but not better.
Only when starting playback part way through.
Not associated with a particular point in score, deleting earlier parts of the score or removing instruments, moves problem further on towards the end.
Easily reproducible for a particular score although the effect is fairly random, never happens on other larger / smaller scores , as yet I have not identified the difference.
Export as mxl and re-import from mxl does not solve the problem.
Looks like a timing / unset variable.
Am installing on a slower computer different OS to see if the effect is different.
Keep you posted with, hopefully, a simple score that shows the problem.

See http://musescore.org/en/node/279206