I have just tested this on my side, and the state saving is working as intended. I'll list a few things below that may be worth checking:
"State Saving" must be enabled on the EFB prior to exiting a flight (the State Saving box will be light grey on the EFB when enabled). With State Saving enabled, the aircraft's state at the time of exiting the flight will be saved, and then reloaded the next time a flight is started in the aircraft. The State Saving should cover all controls in the cockpit, as well as external equipment such as the Chocks, Tie-downs, and Towbar.
Ensure the simulator is closed down correctly via the Main Menu, rather than using Alt+F4 or Task Manager to force it to close.
We don't officially support any of our products on the MSFS Sim Update Betas. Although you mentioned it in your post, I thought I would bring this up just on the off chance that you were using the SU4 Beta. The Sim Update betas are beta releases, so bugs are expected, and we have seen some odd behaviours like this in previous betas.
Mark - Just Flight