I've installed all the necessary mods, restarted the game several times and even though I can see that the boundaries have obviously expanded outward in a random city, I can't place anything outside or INSIDE of the original boundaries.
I started a new city, built some roads, restarted it to get the limits to expand, but after restarting I can't plot anything anywhere (apart from roads, both regional and otherwise). Zones aren't visible when selected and nothing plops no matter where I put it. I tried doing this with an already-built city and I had the same problem.