I cannot believe that a problem I have reported at least twice, last time was 2018 still made it into Fences 4.
When you have 2 separate fences desktop pages (i.e. switched with ALT+arrow) and you attempt to move one icon from one fence from page 1 to another fence on page 2 by dragging it to the desktop edge to switch page and then drop it into the destination fence, the move will fail if you drop it in an area of the fence which overlaps with the source fence of page 1. I.e. if the fence on page 2 has the exactz same dimension and position then the fence on page 1 you will be unable to drop the icon in that fence. While if the destination fence is larger (which is the case in my scenario where the destination fence nearly fills then entire monitor) you can drop the icon in any spece of that fence as long as it is not (virtually) "overlapping" with the source fence.
I do not know if this is linked to the fact that I have 2 monitors or also on single monitor configurations.
The graphic bellow shows my fences layout documenting the problem. Each color block represents a separate fence. Horizontally are shown the two monitors, while each line of monitors represents the layout of a fences desktop page. On page 2 there is in this graphic only one single fence (in my current setup there is a small single icon band icon fence above that one. So 2a, sb and 2c are only for th eexplanation, actually all belonging to the same fence!
The fence marked "1" is my default fence. If I now want to move an icon from that fence to fence 2 (on page 2) I can drop it in areas 2b and 2c which do not virtually overlap the space of fence 1, but if I drop it in region 2a it will return to fence 1.
Note that the problem is not linked to the default fence, when I first drag the icon for example to the light blue fence just right to it, I have the same problem if I attempt to drop it on the "overlapping" top part of 2b, while dropping in 2a, 2c and lower part of 2b will work fine. Also in case of the problem the icon will return to the source fence, not default fence.
I have seen this problem over many years with several different computers and windows installations in windows 10 and 11.