Dorico Thumbnail Extension not working in Sequoia

I cannot get my Dorico project files to show thumbnail previews in Finder. My older projects all show previews, but if I open them in the latest version of Dorico, the thumbnails are replaced by the Dorico file icon. I updated to the latest version of Dorico (Version 5.1.60.2187) before I updated my Mac to Sequoia, and this problem began with one of the recent Dorico updates. I assumed that updating my OS to Sequoia would correct the problem, but it hasn’t. I made sure that the new extensions are turned on in Settings. I have tried reinstalling Dorico, I have reset my thumbnail cache via Terminal, and I have zipped up the affected Dorico files to make sure that the PNG and PDF preview files were generated (they were). Does anyone have any other ideas?

You might find this thread instructive: Quick Look not always working in v. 5.1.60 - #14 by Richard_Lanyon

Thanks, Leo for that link. I already read that thread and three others with similar problems. My problem is different, and I think now it has something to do with my computer. The files are all stored in an iCloud directory, and they show their thumbnails on my computer at the church. That computer is still running Sonoma, but it has the latest version of Dorico. Also, I almost never use galley view. I know the thumbnail images have been generated, but they just will not show on this computer’s OS. I do not think the problem has anything to do with Dorico, but I thought maybe someone might have some insight. My guess is that one of my other apps is interfering, and I will probably have to do a clean install of Sequoia.

Have you turned on the QuickLook extensions in System Settings > General > Login Items & Extensions ? (Scroll down to “QuickLook”)

You NEVER need to re-install the OS. It is on a read-only, secure volume that will not boot if it’s been modified. Re-installing things rarely fixes configuration issues, either, because it’s all the plists and SQL databases that hold that data.

You could erase all the User data, but that’s a sledgehammer approach.

Hi Ben,

Thank you for jumping in here.
Yes, the QuickLook extension are turned on, as I said in my original post.

I pretty well think of you as the God of all things in Dorico that matter to me, but I have to disagree with your last point. I have had problems with Spotlight/Quicklook before that were only resolved by wiping my system and reinstalling the OS. Maybe that was the only option I thought I had; I have one or two apps on my computer by a sketchy developer, and the addition of one seems to coincide with this issue. I would LOVE for you to prove me wrong here, but I am sure you have more pressing concerns. My user data is all backed up.

You should only need to wipe the user “Data” volume at most – but of course you then need to be careful about what you restore. (And you can brick the M-series Macs if you erase the entire disk.)

I’d start off by testing the behaviour in a brand new user account, for starters. (Make sure you can access some Dorico files from there.) That will rule in or out user prefs, and also any user-triggered processes.

That’s certainly something easily testable. Remove it (including any Launch Agents, Helpers, etc), restart, and see if things improve.

I created the new user account (great idea), and I copied a couple of the newer Dorico files (without thumbnails) into my Public folder. I logged in to the new account, opened system settings, activated the two quicklook extensions and then restarted the computer. I logged back in to the new account, activated Dorico and opened one of the files. I used “Save as” to save the file to my desktop, and the thumbnail still did not appear. I can get a beautiful quicklook preview of the file but no thumbnail. All of my older files show thumbnails, but as soon as I open them and save them in the newest version of the app, the thumbnail disappears.

I also deleted the app that I thought might be causing trouble. I tried to find all the support files in my user library and delete them too. Still no luck.

I did “Erase All Content and Settings” and reset my Mac Studio (Sequoia 15.1.1) today, and this problem persists. It’s baffling to me.

I installed a couple non-native apps before Dorico – Adobe Creative Cloud (including Photoshop, Illustrator, InDesign, Acrobat, and Media Encoder) and Dropbox before installing Steinberg’s Download Assistant (and then Dorico 5 latest). I activated the Quicklook Extensions and rebooted the computer. The thumbnail icons will not show on any files created in or edited in the latest version of Dorico.

If I change the file extension to .zip and then “unzip” it, I can see the PDF and PNG files that would be used for Quicklook; the Quicklook preview works, but the icon still does not. This is really a small issue, but it’s driving me nuts – obvious, if I am willing to spend an entire day resetting my computer. Are there any knowns issues between Dorico’s new quicklook extensions and Dropbox or Adobe apps?

I have been in communication with Richard Lanyon, and it looks like this problem may not be with my system. They are looking into something with the app extension for Mac that might be able to resolve it in a future update. Thank you, Ben and Leo, for trying to help.