Used that lock on our prop for the last couple years.. never had a problem.

I just noticed that the prop lock does not have/allow the “tabbed” retainer ring (as the ring cannot hold the nut (due to the smooth cylinder used for security). I have not had any issues with losing props...but I also don't want to start having issues.
What is anyone else doing about this?

I have never had any issues. It is at least a deterrent. .

My port side drive would loosen the prop lock, somehow, and the PO lost a prop. I have been using blue locktight and have not had the lock loosen up. My middle and starboard props are not doing this with the locks. Not sure why one does and not the others but the blue locktight solved it.

The washer those come with is actually a "belleville" washer. It has a slight cup/spring action to it and when nut is tightened, creates a load on the nut acting as a lock washer. It may have lost its tension and needs replacement, or PO didn't realize it was anything special and replaced it with a flat washer instead.

Just don't loose the keys !! If you have the original packaging, write down the serial numbers so you can get a replacement key just in case.

Very informative...I will study/inspect the current washer.

Done...thanks!

Blue loc-tite...got it!