Hello, I have checked audit trail of your synchronization group operations and I can't see any deletes to be done in the chain of operations, so most likely the data are there but are just not visible for some reason.
Could you please start both computers make them running and keep them connected to the internet at the same time
add new record manually (e.g. secure note) on each device and check they are synchronized?
means note on PC 1 appears in notes on PC 2 and vice versa