AI Denoise Not Working

I have an Imac 27" "late 2015" desktop, 32GB RAM, OS Monterey version 12.7.3 with a 32GHZ Quad Core Intel i5 processor and LR Classic version 13.1 release. 

After having no issues at all with the AI Denoise feature, in the past few days it mostly does not work at all. Maybe one in ten efforts provides an enhanced dng. This happens with ISOs from 200 to 12800 and any exposure time, fstop, etc. I start my editing process with this feature every time. It will show me that it is going through the usual processes and looks as if it's going to produce the enhanced image, but at the end shows me a blank gray loupe view with a single message "No Photo Selected" in small type centered in the screen. No enhanced image appears. I have tried restarting LR and/or the computer with no results. I back up the app daily and sometimes optimize the catalog after a few hours of editing. All other editing processes work whether global or selective. I have thousands of images from France, Italy and Spain shot indoors where tripods are prohibited and do alot of long exposure night photography so this issue has paralyzed my editing efforts. Does anyone have any suggestions as to how to fix this problem? Thanks in advance.