I have non-rollup fences. I don't think I have seen this issue with files created via "New" context menu. I think it's always been with newly installed program shortcuts.
To test with newly crated files I wanted to disable previously configured rules that all new icons go to predefined fences. I disabled it, but they still ended up in that fence. Tried disabling/enabling Fences, still the same. The removed that fences and was able to test with files from "New" context menu. Didn't see the issue, files were places where I had opened the menu.
So, it appears there's also an issue with applying the "new icons" rule change to fences.
I now tried to install Opera Browser to see where icon gets placed. It ended up at intersection of 4 displays. Here's screenshot https://i.imgur.com/Tqcp1ZM.jpg
Not behind fences, but in seemingly random location.