Take a good look where the 'bottom' of the arm attaches to the side of your RV. Check to see if it wobbles or the bolts are coming loose.
These bolts only go thru the subfloor which is particle board and very thin. These bolts start getting loose and when you bring the awning down and up it's slop is just enough not to be to unhook the top of the arm. Or in the case of going up it will not lock in properly. Usually if you push arm up just a little it will unhook.
My mobile RV repair sees a ton of these. Fix is going inside and putting steel plate a screwing outside bolts to them. Check to see if those bolts on the bottom of the awning arms to see if they are getting loose!
Sadly on one of mine the bottome of the arm attached right at the side seamline along my MH and it pulled it away allowing water to seep into the floor. :{ Mine became loose during high winds and I never noticed it until it started hanging and wouldn't lock on top or come down.