Importing mp4 video (out of a GoPro) into Photoshop CS6. It used to work perfectly a few mths ago. I always keep my S/W up-to-date. Now (after various updates) I only get the sound track opened correctly in PS (which seems perfect) but the video is blank. While importing, it doesn't show the long "import video" window with the blue progress strip. The import is fast but video is blank. The timeline is correct for the sound but the blank video strip is usually very truncated. I've tried various ways, dragging the video onto PS icon, using the + sign in timeline etc etc but no action shows the video. Last Fall I edited several videos without a problem. I'm not a big video person but this feature in PS CS6 was very handy.
I use a MAC Pro (desktop) with 12GB RAM and flush the cache regularly.