PDF files not opening in Quick Look or Preview after iOS 27 update

Hi everyone,

Is anyone else experiencing a complete failure when trying to view PDF files on iOS?

Ever since updating to iOS 27, my device has lost the ability to open or preview PDF files using the built-in Quick Look feature and the Preview app. This is the second time I have faced this issue—the first time was on iOS 26, where I was forced to do a complete factory reset to temporarily fix it. Having to reset the entire device every time this happens is not a viable long-term solution.

Specific Symptoms:

1. Grey Thumbnails: In the Preview/Files app, all PDF documents suddenly turned into blank grey boxes. These are existing files that used to open fine, so the files themselves are not corrupted.
2. Default App Assignment Loop: When I try to set a different app as the default viewer (Long press file → Get Info → Open With), the selection reverts immediately. Even if I select another PDF viewer, confirming the change forces it back to the top item on the list (which isn't even a PDF reader).

Troubleshooting Already Attempted (None Worked):

• Standard restart and hard force-restart.
• Deleting and reinstalling the Preview app; offloading and re-downloading the Files app.
• Selecting "Preview" via the "Open With" menu.
• Connecting to a Mac via Finder/iTunes to update/re-install the system.
• Running third-party repair tools (e.g., iMyFone Fixppo).

I’ve seen reports of similar bugs dating back a few years without a definitive fix beyond a full factory restore. Given how fundamental PDF handling is to daily tasks, this feels like an OS-level file-association or rendering bug.

Has anyone found a workaround that doesn't involve wiping the phone, or discovered a specific app conflict causing this? Any insights would be greatly appreciated!