Just an Idea
When we first got our 25FB we had the same problem. The drawer was almost always open when we got to where we were going. I had been reading about over hitching and how that produces rough rides, popped rivets and open drawers.
We inherited an Equalizer hitch with the 1K bars which I was, and still am, very glad to get. After putting on a set of new tires I cleaned and greased the hitch. I also dialed it in to my setup and feel as though it looks and feels right. I reduced the tension on the bars a bit but still have a nice level trailer.
We did notice a missing rivet when we got the trailer and one popped not long after we had it. They have been replaced and nothing has happened since I reworked the hitch. The drawer stays shut as well. It was open once after a long drive on a washboard forest service road but nothing else.
Perhaps your hitch is a little tight?