Manually added state not placing provinces or burgs on regeneration/recalculation

First, thanks for this excellent resource. I've only just started to get the hang of it, so if I'm missing something obvious I appreciate being schooled by those who are more familiar with the map and its tools.

My issue is that I can't get more than one burg, the capital, to show up in a state that I have added to a map I'm working on. It almost entirely occupies land that I've drawn in with the edit heightmap feature (using the erase option to avoid issues with the other options). I can place burgs and provinces manually, but whenever I use the regeneration/recalculation feature it reverts back to just the single capital location with no provinces or other burgs throughout the empire.

I'm assuming that there is some setting I haven't gotten right, or some feature I haven't added correctly to either the land I painted in or the state as I added it, that is making it so burgs don't appear. I thought it was an issue with biomes, but I've altered the biome through both the "configure world" function and by manually editing the biomes within the state but neither of these has affected the issue. It also seems to not want to extend any religions to this area, but I'm at a loss as to what I need to do to get this land to be included in various calculations.

I've attached an image of the map for reference, names and some other details are placeholders for now. The state in question is The Empire, and it occupies the bottom left of my map (which is a northern latitudes map). The land it occupies is an extension of a continent which otherwise has many burgs, provinces and other features (much of this functioning land north of the empire was already in place from the seed I started with). It's currently set to generic growth model, with an expansion value of 8, and my growth rate is at 1, but I've moved these settings up and down and seen no change.

Many thanks to anyone who reads this and offers some advice.

edit: Sorry, i have posted this twice now, and both times the attached image has failed to post. Maybe I should just give up on technology and move into the woods.