I've always had this trouble and have searched for an answer numerous times. The closest I've found are threads related to Inventor and Solidworks thumbnails not showing up. For me, the thumbnails show up fine but the preview pane in Opus doesn't display anything. Windows Explorer preview pane; however, is able to display the file's built in preview image as it should.
I am running 64 bit Solidworks and 64bit Opus 11. The file extensions for Solidworks are "sldprt", "sldasm", and "slddrw".
Is Explorer's preview pane just showing the file's thumbnail?
If the preview won't go larger than 256x256, and looks identical to the thumbnail when Explorer's thumbnails are made as large as possible, then that's probably what it is doing.
The preview pane in Explorer falls back on showing the file's thumbnail if no viewer for the file is available. Opus doesn't at the moment, but you should be able to see the same image in thumbnails mode, or using the file's infotip if {thumbnail} is included in your infotips.
Thanks for the quick reply! That's exactly what it is doing. I have been hoping to find the feature added to Opus but you confirmed that it still doesn't do it. Do you know if there is a plugin out there somewhere that would force the functionality? I believe the preview image is an embedded PNG but I'm not 100% sure.
Actually, exactly as you stated, all I am looking for is an enlarged thumbnail when Opus is unable to preview live content... to explain why this helpful:
When I release a design project I open a list of files consisting of Solidworks native (sldprt, sldasm, slddrw) and PDF, DOC, XLS, etc. In the lister, I open up the preview pane and I scroll down the list of files inspecting the full file name as well as the content of each file. You can see where Explorer would have a less disrupting workflow in this regard, because it is able to display the thumbnail, where Opus has always shown a blank for these native files.
I wouldn't expect Opus to be able to display the "real" 3D content of the Solidworks files (or any format that doesn't have a full preview handler available), just as Explorer cannot, but it would be immensely helpful if it too, could just default to showing the enlarged thumbnail. What I am forced to do now in Opus, as you suggested, is toggle a large thumbnail view but then I lose the concurrent detailed view (and live previews for the other file types). It is not the same functionality as scrolling down the detailed list and inspecting the viewer pane. I hope this makes sense.
The change is pending testing and translation, so it won't be in the very next updates but shouldn't be too far away. (e.g. It probably won't be in a 11.4.x beta or the 11.5.0 stable, but will hopefully be part of the 11.5.1 beta that will come after them.)