Hello everyone! I see that some people have had the weird bug of the greased achievement not working.
Well I got it a few weeks ago and hopefully this will help.
I restarted my landing challenges from the beginning
I was half way though the landings and started back in Sim Update 2 or 3
I also got the achievement after redoing the landing challenges until I found the one that the sim “missed”.
This is very common in case your logbook gets erased by an update, as it happened to me (twice, with SU5 and SU7) and many others.