I suspect my issue is similar.

Each time a new day clocks in my work order priorities reset to a previous one it also happens when I load a game from a save.

What I have figured out is that it is related to the default work order policys simply not saving, but reverting to whatever it was when it was saved the first time (new work order policies save as you would expect).

Edit: Oh it's a Better Pawn Control and Work Tab conflict.. I seem to have solved it by moving Work Tab to the very bottom of the list even though that hurts my soul, 'cos it belong in Functionality/UI/Game Mechanic section.

I may have fixed this by renaming the default work policy from default to something else.

Hmm, I don't have "Better Pawn Control" and moving it to the bottom doesn't fix it. Guess I will go back to the default tab. Bleh. Oh well.

Try out complex jobs stable perhaps obstructor?

I just as of the other day starting having this issue as well. I do have Better Pawn control. Not sure what changed to suddenly make me start experiencing this bug.

my error must be the same, but also different.

Only part of my preset are reseted to unckek box, and found why just now !
If a pawn can't do a job, he reset ALL the priority for ALL Pawns with same preset !

here is a screenshot :
https://imgur.com/a/2zFnze7

i have almost 400 mod, and work tab is the last in the list, there is perhaps mod compatibility issue... but i hope this can help to fix it because we are a lot with this bug ^^

I think my issue might be related too, albeit a bit different. I have no issue when I don't use the time schedule, but when I do it resets as soon as i close the work tab...If i make any change while time schedule is active it gets reset as soon as i close the work tab to what it was before i started setting priorities for certain hours