step 1 - open Topaz AI from Lightroom plugin
step 2 allow Topaz to process a file (no adjustments made)
Step 3 click “save” which says “save to Adobe Lightroom Plugin”
Step 4 allow Topaz to process but comes back and says “cannot open output file”.
Note:
I have been unable to process the last 3 updates (and several previous ones as well, so to get around this I have been downloading the latest version. I have Lightroom on D drive and Topaz on C drive
Try sending a TIFF with LR edits applied via the edit in menu to see if that makes a difference.
Where you are saying you haven’t been able to process the latest 3 updates sounds as though you don’t have sufficient access rights to save images to the D drive.