Browning Maxus Cycling Issues

I purchased a new Maxus this past January. My primary use for the gun is duck hunting. This past season has been my first season hunting with it and I had nothing but problems all season long.
First off - I can 100% assure you that the gun is clean each and every time I go hunting. I have disassembled the gun completely and cleaned it as thoroughly as possible. I use CLP when cleaning.
With each hunt, the gun would cycle fine on the first 10-15 shells. When I would get to around the 25 shell mark - that's when my issues started.
The action became noticeably slower. I could count 2-3 seconds before the action would complete it's cycle.
I sent the gun to Browning once. They completed 'minor repairs' and returned it. I cleaned the gun, then shot several rounds through it from 2.75" to 3.5". When I got to around the 50 shell mark I started having the exact same problems.
So I called Browning again and sent it back to them for the second time. One of their techs called me as soon as he finished putting several rounds through it and told me they couldn't get it to replicate the problems that I described.
So...that leads me to this assumption - it has to be something related to cold weather. Has anyone experienced anything similar to this with your Maxus, or any other gun for that matter? If so, what fixed it?
This gun is driving me nuts.

Sounds like it could be ammo related. Some of my hand loads don’t like the cold.