This may not apply only to windows explorer , but this where i have noticed it most and seems to happen on both automatic tab groups and on manually created groupings
When you group Windows Explorer windows and move to another screen it appears that the other window positions in the tab group don't follow the group , and the tab group will jump back to their original position on the old monitor
this seems to be intermittent but happens pretty often
it seems to go away temporarily if you unmaximize the screen and happens more often when the windows are maximized on creation