XnView Software

It sounds POSSIBLY like a codec issue. You can install a full boat of codecs at
https://www.codecguide.com
Unless you need all the extras (like a video player) get the small basic package
They are free

Right clcik the toolbar and choose "customize"
Then on the top left you will see "new bar"
Move that to the bottom of the right side and start adding items from the left to the righ

I build a new toolbar for use in full screen mode to do exactly that

Settings / browser / Thumbnail and the appearance tab
Is that what you were looking for?

What would be the best way to get around that? I loaded it in Photo, duplicated the layer, deleted the duplicate layer and saved it and that opened it. Also opening it and rasterizing it fixed the issue Stripping out the metadata via XnViews batch converter didn't work. While I didn't try everything...

Please explain a little more what you are trying to do
If you want to keep the program closed and yet view or manipulate photos from Windows explorer then use the shell extension
https://www.xnview.com/en/xnshell/

Thanks for all your effort. You are appreciated

Go into the settings and then Browser / file list / custom filter and start playing around. Uncheck folders and see if you get what you want

VIEW / Show files in subfolder. Note the little icon next to it as it is also on the default toolbar
That will show every file in that folder and all the folders beneath
It is quite handy

You may have several vertical tabs (Folders, Favorites etc) Click one of the other ones then go back to folders and it will be there. It is a graphics issue I believe
If the entire side panel has gone then go to view / layout and pick your layout again

The performance issue is definitely caused by the large amount of Categories (2900+ in my case). It impacts all the regular usage of the tool, for example if I just doubleclick in Total Commander on a regular, unkeyworded photo, the loading time of the photo is very slow and I have to wait several ...

Tools / Settings or just hit F12 and follow the previous post. Please let us know how you make out

Try going into SETTINGS / VIEW and make sure that the reset is checked on the view tab

Does it always open correctly in Windows explorer? If so you set it up correctly now in XcView try opening it with F3 rather than double clicking

0.96.1 x64 on Windows 10 x64
Thumbnails formerly showed the checkerboard background to indicate transparent areas
It has disappeared in this version