Second city won’t load in single player mode

It may still be a server issue, even my private game with no external players is not syncing instantly like it should. Townhall addons when placed apply to the region automatically same goes for the HQ for specializations (usually), there is nothing more that you need to do

If your city is out of power for whatever reason it seems to take a while after you get a power plant online for power to reach the entire city. First a power plant has to get workers, then after that it seems to take a while before it actually starts supplying power.

Buying power from other cities may be buggy. I played a city for several hours buying power from neighboring cities; then saved and reloaded that city the next day only to find the city without power despite power still being available in the region (it is possible that not enough power was available) so I broke down and built a power plant and observed the city slowly get powered up.