MS Office - Opening files in Protected view is broken

About 10% of my users have suddenly been made unable to open documents in protected view. Turning protected view off is not a secure option - And if we unblock file or open from a trusted location it works fine - its just protected view.

Saw some posts about graphic drivers, tried rolling back/updating to no avail, and microsoft support suggested we delete the office folder in our registry to have it rebuild - Also no success.

If the same file that won't open is copied into a folder that is set up as a trusted location, it will work fine. The issue is specifically opening files in Protected view. Impacts Word and Excel.

Preview and opening files directly from outlook classic is also broken for these users."new" Outlook will preview Word docs, but not Open by double clicking.

Just wondering if anyone here has run into this and how they got over it.

Update 2025/05/20:

Some more details about this: every single case has been Windows 11 24H2, 10.0.26100.3775. All our laptops (Latitude 7420, 7430, 7440's) have been affected. Trying to see if there's a specific version of Office impacted, or if its all. It still occurs after an online repair of office so I think its more Windows based. Issue occurs with office version 16.0.18730.20168 and 16.0.18730.20142 whcih is what most users are on here.

If the computer has 24H2 10.0.26100.4xxx the issue doesn't appear to occur, but our sample size is small. Pushing a couple affected computers into targeted group to see if they still have the issue when windows is updated above build 3775

Update 20205/05/30:

Installing old version of office (0824 build, Semi Annual channel enterprise) "fixes' the issue, but is time intensive and results in an outage to the user.

Issue occurs with both 32 and 64 bit office, with windows build version 24H2 .3775. Updating to a later build doesn't seem to fix affected machines for me. But there are machines on later versions that don't have the issue. Seems AV Agnostic.

Microsoft seems to think that going hands on with every machine, Uninstalling office, rebooting, and re-installing office (as well as changing our update channel) is a "fix" and is asking to close my ticket, as this issue hasn't been reported by anyone else.

If you can please open a ticket with Microsoft, it'll get this attention.

Edit: June 4th:

Microsoft tried to close the ticket on me, because the "workaround" is in place. (To use a year old version of office, deployed manually via ODT.)Unfortunately it auto updates, so you actually have to stop updates as well. Change your office channel for your org, and use a year old version of office.

One person below reported running word/excel in windows 8 compatibility mode fixed it. I passed this along to microsoft and we'll see what they say.

June 5th:

Finally getting escalated.