Mine does not snap on my unsingle as easily as it does on the O/U, I just keep a little bit of pressure on the forearm and push the latch down and it hooks just fine. If it absolutely wont hook I would send it to Omaha and im sure they could fit it better for you. Their turnaround and service are great.
If it's like the overwhelming majority of latches I've seen, the hooked part of the latch hooks around the front edge of the lug hanging down from the bottom of the barrel. If you'll examine the front edge of that lug closely, you'll likely see where the bluing has been worn off a little bit. This is the area that I would use a little bit of wet/dry sandpaper or any mildly abrasive file or stick that will fit. Heck, a nail file might do the job.
Wrap some tape around your barrel in that area to protect it in case the file or sandpaper should accidentally contact it while doing a little filing/sanding on it. Go easy with it.