I am planning a trip to Thailand. Curious if anyone has attepted to bring a drone into the country and if you had any issues? I will be flying with ANA, United, and AirAsia.

I would look at the government website to see their rules.
And also look at each airline's rules.

Im not from the USA but have flow into Thailand many times with my drones and never had issues ( goes without saying batteries need to be carryon - I take the drone too ). Internally I have flown with ThaiSmile, Thai Airways and AirAsia without any issues.

As Ken says, check airline conditions but most follow the same rules.