The Blob Cache downloads files directly to the target file location.
While it tries to clean up failed attempts, there is a change that this cleanup does not complete.
In that case, we have a corrupt file at the target location. The blob cache then assumes that it already has the file cached already and future requests do not attempt to re-download the file.
The fix would be to download to a temp file name, validate the integrity, and rename to the target file path when the validation succeeds.
The validation for "content addressable" could even include validating the checksum hash.