Help! I can't recruit units. Instead of the possible number of units I can recruit, I see this:

I had this happen after upgrading a hero's skill that increases army growth, but I upgraded it in the campaign map and for the hero on the left, so there were enough troops. Otherwise, you'd have to restart the map or the campaign from the point where you upgraded the skill.

Added 4 minutes later
Regarding the "Mass Recruitment" quest, I completed it.
I noticed that when you approach the required location, but are just a little short on movement points to reach it (1-5 movement points), the location stops working. I loaded an autosave, approached with enough movement points, completed the quest, and recruited the necessary units.
Maybe this will help someone.