Whilst creating a folder portal with click-alt-drag, I managed to get 2 sets of the icons sitting on a different page, with no fence.

I could highlight one set, but not the other, and could only remove all of them by deleting them from their original folder.

I can easily create the portal by left-clicking in windows explorer, or right-clicking on the desktop.

It's strange, being the only problem I've had whilst creating four folder portals. I can only think it has something to do with my dual monitor setup, and the fact that the folder is synched with Google Dive, which I only turn on to backup up work (it was turned off during this process).

 Hmmmm... they came back after a reboot.