Hey Tom,
Sounds like you need to trash your cache:
Clear Media Cache on app launch
Before updating to a new version of the app or identifying and resolving app problems, use reset options in Premiere Pro at launch to do routine maintenance and cleanup on your system.
Press and hold Command (macOS) or Ctrl (Windows) while Premiere Pro launches to activate the reset option. When the Reset options dialogue opens, select Clear media cache files.
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Inside PPro:
Select Edit > Preferences (Windows) > Media Cache or Premiere Pro > Settings (macOS) > Media Cache.
To remove media cache files, click the Delete button next to Remove Media Cache Files.
In the Delete Media Cache Files dialog box that opens, you can choose to:
- Delete unused media cache files – Deleting unused media cache files removes files that were created for source media that can no longer be found.
- Delete all media cache files from the system
– Deleting all media cache files deletes all cache files from the
current location. Deleted cache files are recreated automatically
whenever source media requires them. To remove all media cache files,
restart Premiere Pro and select this option before opening any project.
Click OK.
Note:
- To delete all media cache, select File > Close All Projects. Now select Preferences (Windows)> Media Cache and Settings (macOS) > Media Cache.
Or, my least favourite to suggest to you, as I keep my Cache files in a separate location:
Delete media cache files manually
With Premiere Pro closed, navigate to the location of these folders and delete the files manually. After you delete the files, then empty the trash.
File locations:
Mac: /Users/<username>/Library/Application Support/Adobe/Common
Windows: \Users\<username>\AppData\Roaming\Adobe\Common
Deleting the files manually with Premiere Pro closed deletes the current media cache files, as well, which is what you want to do when troubleshooting errors.
After deleting the files, you should see additional hard drive space become available. If you have older projects you have completed, it is a good idea to delete these files to save storage space and to keep your computer’s hard drive tidier.
Remember that a delay occurs after you delete all cache files and open a current project, as the files need time to rebuild. If you have a large project, budget enough time for the media cache files to rebuild. This can be done overnight, for example.
All copied from:
https://helpx.adobe.com/uk/premiere-pro/kb/clear-cache.html
Hope that this helps.
Atb
Mads