Adding my opinion here. From what you describe I think the brake shoe friction linings are rusted to the brake drums. Usually you can break them free by rocking the car forward and reverse. You might be able to break them free by prying against the shoes through the adjuster port of the backing plate.
This usually happens when the ebrake is applied when the brake shoes are still wet or got wet afterward. If you do break the shoes free, you will probably experience a jerkie application on that wheel until the rust has been worn of the drum.
Hope that is what it is. Good luck.