Well put Chad. My PP does the same (heel to a sit) and I'm sure that's due to the repetition of the 2 commands in back-to-back sequence so many hundreds, maybe thousands, of times.
I would like to get that "bug" worked out, but there are bigger problems out there. I fully agree to getting the same side worked out and driven home...not sure what handed shooter you are or if you hunt alone alot, but that is a must. Whatever side it is, make sure that's the one you work at...with correction everytime your pup jumps to the opposite side.
I taught to work off the lead if it's working well early on and jump back to a lead every now and again to drive it home, especially if there's even the slightest bit of correction needed. It doesn't hurt for them to remember who's in control and what is expected. Basically, it's the same concept as anyone that started their fresh-at-home pup on the "come" command using a check cord....just going back to it for reinforcement.
Good luck.