The good
DoctorOhh threw/bowled me a curve ball/googly - see
Error Interpertation
As a consequence I unchecked LRF in the
Use internal viewer for list, and I changed the Windows association from ebook_viewer.exe to lrfviewer.exe.
Then I tried to repeat the scenario where I got the Attribute Error - but I didn't get the error. But maybe that's because I hit the Use Defaults when I did a manual conversion.
BR