XYplorer Beta Club

First instance of this.
I was opening XYP in two screens
Opened a folder of images, and this occurred.
The images are all there, I checked opening ACDSee
If I click on the black square, the image appears.
I have tried "refresh Folder" no go.

Any tips please?

View | Caches | Refresh Thumbnails

Like Magic!
Thanks Jupe

If two instances share the same thumbnail cache folder, this can and will happen in one of them when new thumbnails are created in the other.