I can confirm after many tests in 3 different maps that there is for sure problem with resetting stats of Stat Creator Device while there is no obvious reason for it to happen.
I made a thread about it in December, but few days ago I added new info that you could find interesting, becouse I found out what to do so the resetting of stats is not happening (it is not really a fix, but it is better than nothing at this point, becouse when players can lose their progress, that is really very bad outcome which should be addressed as soon as possible): Stat Creator is resetting Value for Players who Join In Progress - #5 by locutus