My awning also has a clip on each arm that must be released.
I'd take a photo but it's dark and snowing here!
In order to pull open my awning I have to
A- flip the latch from close mode to open mode.
B- loosen both hand wheels
C- pop out the latch on each arm
You say you've done A and B but did not mention C.
This is an anti rattle latch and it's barely visible when closed.
Look for it and if you can't find it we'll take a photo and also
talk about which brand you have.
You probably have a Dometic (A&E).
Here is the operators manual but the sketch of the clips I mean
is really bad. You'll find them when the sun comes up!!