Hm, if we have to alter the files name, what good does the "reload textures" do anyways?
I have checked the suggestions for using tiff files insead of png or jpg.
The reloading did not work any better, but the file size got higher, so I received the "Running out of memory" message.
Unchecking the Cache in the render setting did work, but I also had to clear the Render cache in the General Preferences under the Render tab.

I do think those "Bugs" get often noticed after an update because people seem to be more aware and almost expect to find something.