It came with the treeless I bought recently. At first I thought I was just not doing the girth up tight enough because it would be pretty loose at the end of the ride. Then I realized it was actually looser becaue the tie strap was loosening. I tie it rather than use the buckle.
I plan to switch it out to a leather one but have never had this problem with a nylon tie strap before.
Any idea why this is happening? There is a nylon tie stap on my husband's saddle and that one never comes loose. I find it kind of odd.
Sometimes if it's new and particularly thin, it'll be more "slick" but you might get a tighter knot. If it's worn a bit or thick, you might not be able to get the knot as tight and prevent the slippage.
I bought the saddle used and have no idea how old the latigo is. It is in good shape. I don't have it here to look at but want to say it's thinish. I hadn't realized there might be differences in nylon latigoes. I'll compare mine to the one on my husband's saddle and see what the difference is.
I'm still getting a leather one but did wonder what was up.
My BO lets people borrow her saddle -- it's a Tex Tan with a nylon strap. That one I have no problems with since the nylon seems to be thin with a very tight weave. Another saddle that's in the barn that the lesson kids use is a synthetic saddle that has a fat nylon strap with a really loose weave. That one is a PITA to keep tight. I'd assume that if you were to swap the two straps, the synthetic with a thin tie would be similarly as easy to keep tight.
I changed it out for a leather one and no more problems with it coming loose allowing my saddle to slip, not even when I found myself momentarily dangling after catching my shirt and jacket on the horn.