I had an issue similar to this when I was parked at a client site near a cell phone tower. Even went to a local auto zone about 200 feet from where I was having issues. Got a new battery, still no luck, had to hold key against start ring to start and use the physical key to get in. Personnel inside stated that most people near that area cannot get their cars to lock and unlock remotely due to the nearby tower.
Haven't been back to that client since, however it is kind of a pain when the remotes don't work in all scenarios.