Unable to "Delete all repository caches"

My GitHub project uses caches to store download tarballs: https://github.com/spack/spack/blob/develop/.travis.yml#L146,L153

One of these caches got corrupted, and a particular PR could no longer pass its unit tests due to this. When I go to https://travis-ci.org/spack/spack/caches, I see an option to delete the caches for each particular PR, but I don’t see the PR in question. It seems like there is a finite limit on the number of caches displayed, so I need to delete all of the caches before it to see it. However, when I click “Delete all repository caches”, I get a message saying “Oh no! Could not delete the caches”. If I refresh the page, I discover that it actually managed to delete around 20-25 caches, but I have to keep doing this dozens of times to actually clear all caches. Is this a known bug?

Please link to the build in question.

My guess is (without seeing the build, can’t say for sure) that the cache search logic falls back to another branch’s cache when fetching: https://docs.travis-ci.com/user/caching/#pull-request-builds-and-caches

So you need to rather search that branch in the caches list.