When you try to browse for your .swf files via the VideoStudio library, you cannot see them; but you see they are in their correct location when viewed using File Explorer. When you try to drag and drop the .swf files, VideoStudio will not accept them.
Adobe has dropped support for the Flash format and recommended users to uninstall Flash plugins and utilities from their computers as a matter of security. Adobe officially stopped supporting Flash since December 31, 2020. And since the .swf format runs on Adobe Flash, support for this file format has been eliminated entirely from use by reputable software and tech companies.
We are aware that the VideoStudio product website still shows that the .swf format is among the supported video formats, but this has already been brought up to the concerned teams and we are working to correct this oversight. We apologize for any inconvenience this may have caused.
Unfortunately, there are no workarounds to salvage your .swf files. Our only recommendation is, simply, to not use them at all.