Three possibilities:

1. Bad receiver.

2. Shielded receiver. Did you move, store, or mount anything between the operator and the remotes? Metallic objects blocking the signal are most likely to be a problem.

3. Interference. The best bet. Almost impossible to track down without highly specialized equipment, and little you can do about it anyway, unless you are the owner of the item generating the interference, in which case, turn it off or fix it. Start by turning stuff off and seeing if it makes a difference. Suspect everything electric or electronic, including your neighbor's stuff.