'94 Roadtrek with Fiamma awning
I had the same problem and solved it by adding a strip of Duct Tape (approx 12" long in my case) on the top of the rear edge of the awning. In effect, this makes the rear of the awning thicker / bulkier so it lessens the amount of awning that has to be retracted before it activates the catch. It's been working there for several years. Worked for me but if you have a large discrepancy with the amount of awning that needs to be retracted at the rear, probably won't do the trick. I couldn't see how else to adjust it but yours may have a better system.