My GUESS is that gator2 has it.
I learned on R44 and flew then for years. My daughter also. We were both taught that in the mag test, if there was no "lumpiness" and RPM drop when you swapped from BOTH to L or R then there is an electrical problem, and the aircraft is unserviceable. The thing is, with no drop from BOTH to ONE it suggests that when in BOTH you really only have one mag (if the switch is working). As here, it could also show an intermittent fault in the earthing circuit.
A drop of more than 7% indicates that in BOTH you had 2 mags but the mag you are now testing is not serviceable.
I should also add, we were taught to test R first, as it is 2 clicks back to BOTH, then L (one click back to both). That way you reduce the risk of testing R second and only going back 1 click, so departing on the L mag only.
Anyway, if the test does not go as you expect then - whatever the difference - off to maintenance and no flying with me in it until sorted. .