Thanks for that information. I'm getting the same response from the Feedback page. I'll see if I can find out when the page will be back open. Thank you also for that .HEIC photograph.
Videowave filters files at two levels. Firstly it checks to see if the file extension is on the list of filetypes it accepts:
and if they aren't in the list then the files don't even show in the Videowave selector box when you open a folder, and you get a flash of a prohibited sign if you try to drag them in with Windows File Explorer.
Then, if the filetype is allowed VideoWave tries to show a thumbnail of the file. If something prevents that (e.g. it uses a codec that's not installed) then VW shows a 'prohibited' thumbnail.
.HEIC files aren't in the list, so VW won't have anything to do with them.
However, on my unmodified Windows 10 system, MS Paint and Windows Photo Viewer will display files in the .HEIC format, and free programs such as IrfanView and CopyTrans HEIC can be used to convert the .HEIC files to one of the formats in the VideoWave input list.