Than it may be some kind of glitch for me, as I’ve completed normal with 2 characters, and with both of them already completed 1st Act in Elite difficulty (including And Not a Drop to Drink quest) - but haven’t received additional bag to my inventory
I confirm this as my Conjurer just got the 5th bag from a Rover quest, can’t remember which one though. I think it’s one of the quests you get in the Rover main camp in Old Arkovia.
And apparently in elite and i’m guessing in ult after your 5th bag people will keep telling you they’re giving you more inventory bags but don’t believe them, they are lying to you.