When utilizing the mercenary from act 2 I had an issue where my mercenary would not level up. His experience was greater than what was required for his level up and continued to grow. This was encountered on the Online play as can be seen by the game name/password in the top right of the screenshot below
Image of the bug provided at h t t p s://www.dropbox.com/s/pc819854x1enjly/mercbug.JPG?dl=0
Just want to make sure as well. Is the Merc MORE then 1 level behind your character level. Mercs CANNOT be the same level as you and will be locked to the level prior to your current level (but will still gain XP that will apply to the next level up). But the Merc can NEVER be your current level.
The merc was level 15, my character was 23. Have since had to remove his equipment and re-hire a new mercenary in order for it to level with the character
Actually it seems D2R changed this so that now the merc can get to the same level as you. I don’t know if this is intentional though.