OK, I was outside messing with it some more, pulled it all the way out (boy, is THAT fun with high winds!) and tried to get it to retract, after about 4 attempts it went in smooth as can be and it's now firmly closed. I didn't do anything different the last time, it didn't make any strange noises or anything, just decided to work finally. All I know about these awnings is there's a large spring inside. I'm not sure what would make it stop winding itself in when it was 3 or 4 feet from the camper, I couldn't turn it by hand at that point either. I'm really glad it's in, but now I'm a little worried about putting it out again when the winds die down for fear it will be stuck out again.

its possible the "In & out cam switch on the end that you flip for direction of roll is loose causing the cam to stick...a little blast of WD-40 might cure it

Possibly one or both arms are out of alignment or sticking which would prevent it from closing all of the way. Perhaps on the last attempt the wind helped push the arms into place and the awning closed.