Can’t help with the midlift problem but my previous firm had nothing but adblue issues like you say, although I wasn’t aware it was a Actros’ issue I just thought it was the cheap crap he bought… either way he switched to a premium supplier (brenntag) don’t know how much extra they charged but his trucks were hassle free since. They also advised to keep the tank between 1/4 and 3/4 full wherever possible to minimise risk of crystallisation