I reported on something very similar in a recent post in my previous thread where I reported about the drag handles causing crashes: https://forum.shotcut.org/t/crashes-occur-often-and-easily-with-drag-handles/6562/10?u=a.erwin
Most of what I initially reported were thankfully fixed in the August build but there are still some bugs as I mention in the post that I directly linked to above. I don’t remember though if it only happens with the Size and Position filter.
I also suggested in that post if it could be programmed that if the drag handles are taken all the way to the other side that they are still able to be dragged back because currently if you take it all the way to the other side then there is no way to drag it back.