At first I thought I was just hopelessly bad at coding/following instructions, but even when I pair programmed with these folks and followed their every instruction, they'd still want to refactor all of it the next day.
Some people are just never content unless it's 100% written by them.
I sometimes do that with contracts drafted by junior lawyers — and often it's due to having had additional thoughts after seeing an actual "product," in sort of a fail-fast mode of drafting. Could that be part of the explanation in your case?
I've dealt with this before by documenting everything they told me to do differently, with date and time.
Always fun doing code review in a group, having the lead point out a number of problems they have with the code, especially actual bugs, and pulling up the changelog which includes notes from the one criticizing your code, telling you to make those design choices. I've collapsed whole meetings this way, with people walking out and going straight to HR with requests to transfer teams. Really helps to remove the poison from the group.