RTH and OA are great tools to help out with the flying process and I use them for that vs. relying upon them. Will do RTH and even an autoland now and then for practice, likewise will sometimes turn OA off when out in wide open areas and no obstacles to get better performance.
Have not seen a RTH not work, even with signal loss/lost connectionl; however have seen the opposite where get a lost connection/weak signal with aircraft in vlos, press RTH and aircraft starts coming home, signal strength improves, continue to land manually.
How far away were you when you pressed RTH and could you see the aircraft/drone?
Were you around buildings in an urban environment, or trees, or out in the open?
Was your app/device phone on or in airplane mode?
What do your logs show (
upload them to air data, setup a free account), from there you can see your signal strength during the mission, as well as other sensor status. You can also replay the mission and see where signal loss occurs, rth invoked, etc.
If your RTH height is high enough where you are not going to bust up through your airspace ceiling, and no obstacles, try turning off OA to see if it starts moving. Otoh, if the aircraft encountered an obstacle, check your logs, check maps of the area and see what was happening.