Rekordbox Editing beat grid issues

Hi people

Been having a problem with editing the beat grids that drift.
Right so i go into single player mode.
I edit the first downbeat to the correct position and stick a cue point there then I go on editing through the track in the correct way so everything is edited to the right and everything previous stays as is .

After I've gone through the track checked with the metronome and all is perfect I then lock the track.

Now here is the problem. When I go back into 2 player mode all the work I have done goes back to how it was so all the time I spent has been wasted.
Its strange as it doesnt happen all the time.

Also have gone to other edited playlist that I have corrected previously to see they have all gone back to normal and need doing again. This is so annoying .

How can this happen? All tracks are locked
What's also strange is all the added cue point I did while editing are all staying in the correct position but all the grids have moved.

Anyone else come across this problem?
I'm using rekordbox 6 but it also happened in rekordbox 5.

Any help really appreciated 🙌