Tried to paste image on clipboard into a blank slide. Paste resulted in paste of a previously deleted slide into the show and not a paste of the image. This was not a problem in older versions of Impress. I was able to add the image to the slide by first saving it to a file and then loading the image from the file.
I have not observed this behaviour on Ubuntu with various version of LO including 5.3.7, 5.4.2 and 6.0.0.