I can't delete any of my old captures from Xbox Live

I have this same issue too, and it's preventing me from deleting my old Halo MCC captures, which is frustrating!

I do own the app. Captures will not delete from there either.

The captures also do a cycle where it shows all the “deleted attempts” and won’t delete, then it’ll show no old clips I’m trying to delete (it’ll show any recent clips I’ve tried to add) and that’s when it allows me to upload. It also will show all my old clips and screenshots and when I go into recently captures, it shows the most recently added captures to Xbox live. Right now, it is showing 101 clips and when I click on recently captures, it shows the 4 I managed to slip on to Xbox live only. It’ll eventually revert to the 101 clips and not show the most recent ones.

I'm having similar issues. It's like a few of my captures stored on Xbox Live are corrupt. I can't manage or delete them from my console. If I attempt to delete, they reappear a few seconds later. They are unplayable and can't be shared. New uploads will
only show in the xbox mobile app under captures but they change every time i refresh the page. Microsoft please fix!!

I'm having similar issues. It's like a few of my captures stored on Xbox Live are corrupt. I can't manage or delete them from my console. If I attempt to delete, they reappear a few seconds later. They are unplayable and can't be shared. New uploads
will only show in the xbox mobile app under captures but they change every time i refresh the page. Microsoft please fix!!

You explained my exact issue. Way more better.

Unfortunately captures are automatically deleted from the Xbox network after 90 days now. You could try opening the Captures app and selecting "On this Xbox console" from the drop-down list at the upper-left, as clips are not automatically deleted from the console itself after 90 days, although they do get deleted from there over time as you capture new clips and screenshots. It's worth checking though.

What I do is set the console to automatically upload my captures to both the Xbox network and OneDrive, as they are not automatically deleted from OneDrive and it makes it easy to save any ones that I want to keep on my PC. Unfortunately, you can't share clips uploaded to OneDrive on your profile or via an Xbox message, which is why I upload to both.

But yeah, if your missing clips are not on the console itself and you only uploaded them to the Xbox network, they are gone for good I'm afraid.