My workaround for 'lost' preview files in Premiere

I'm experiencing this problem with a comp I've imported from AE. Using CS6. First time I've seen this issue. One thing I just noticed: I re-rendered the comp on the timeline again. I went to the folder where preview file should be and I don't see it there. Don't know where it's going or if a preview is being created temporarily and then dumped when I close Premiere. The empty sequence technique did not work for me. I'm on Windows 7.

I am having the same problem with any warp stabilized clips in my timeline.

Using windows 8.1, premier pro CC. gopro footage. no 3rd party plugins. No NAS just laptop hard drive.

This appears to work, except for Warp Stabilizer effects, which repeatedly become unrendered after restarting application. I am using CC 7.1 and would like to upgrade to 7.2 to see if problem persists, but the company I work for will not allow upgrades until all edit suites and Maya workstations can do it at the same time, so that we are all using compatible software on all systems. Our tech is still evaluating, and we cannot proceed until he gives the OK.

This is very frustrating.  I've actually had this happen to me on CS5, and it's still a problem on CC. (completely different machines.  Completely different OSes)

I'm pretty sure that the work around is a red herring.  You'll probably get the same results if you stand up and run around your chair 3 times while patting your head.  The work around "seems" to work because this issue does not happen all the time, nor with every instalation.  Who's to say what circumstances cause the problem?

This happened to me a couple hours ago, and have been trying to duplicate the issue with another project.  Premiere has some logic that invalidates preview files.  It keeps the files around even if they are deemed invalid for a specific project.  Anyway, this is all happening within the program itself, and it probably happens at load time.

When I watch my (very large) project load I can see it try to load the preview files, but it skips over them.  Since the project file is unchanged since the last time it worked properly, we can assume that there is another mechanism for determining validity.  I noticed that the modified date and time changes on the preview folder every time the project is loaded.  I suspect that this is a checksum, but I have no idea how it's use (or even if it is used).  Though again, we can assume that changing the date on the folder is important, as Premiere does modify it.

Anyway, I have no answer.  I am re-rendering my film, which will take several days.  Unless someone comes up with a work around to fix invalidated previews... I'll just have to accept that this can happened every once in a while.

The biggest thing I've learned from this, and rendering in general, is that pre-comps are your friend.  :-)

I have the same issue on Premiere CC, Win7 - previews are lost many times. There is a Premiere CC class on FXPHD and the teacher presents this bug to the audience as a "well known bug" - so I see that there are probably thousands of users who must live with this stupid problem for a long time. Shame on Adobe. Please fix it finally.

Ran into this issue.  In my case, I had done a SAVE AS of the project to a new subdirectory with a new project name. (Archaic attempt at version control. Heh.) Premiere created a Preview Files subdirectory within there, and it was properly saving any new render files to it.  However, it wasn't loading them the next time I launched the project.  I noticed it was still looking for and successfully loading previews I'd done prior to the SAVE AS from the parent directory where the original project was.  I did a SAVE AS back to the parent directory, and now they're saving and loading fine. 

I did try the solution in the first post here several times, and I also tried copying my newer preview files to the parent directory.  Neither worked.  I also checked in preferences, and they were already set to save in the newly created subdirectory.  If there was some other place I needed to link these, I couldn't find it nor Google it.  I'm pretty sure I've saved a project to a new directory and been just fine in the past, but maybe I'm wrong.

FWIW, if anyone stumbling across this thread has saved your project outside its original directory.  Put it back and see what happens.

And here's my theory as to what might be happening - it is only a theory and I am not a programmer:

When you launch Premiere to a sequence that has rendered previews, Premiere immediately checks to see if the render files are available. If it doesn't "see" them in those first milliseconds, they are ignored and you get a red bar. (In old versions of Premiere, if renders weren't found when/where expected you were given an opportunity to locate them). The problem is, if you have a lot of media in a project, it can take several seconds for everything to load and the render files are last. By then it's too late. Premiere didn't "see" the files in question, so they were ignored for that sequence.

I think this is also the reason why the problem seems to be hit and miss. If you have a small project, all the media including the render files load quickly before Premiere has a chance to "ignore" what it thinks might be missing in the way of rendered previews.