We ran into a related issue too: uploads succeeded, but Cargo couldn't find the new versions in the index.

Related report: https://github.com/rust-lang/crates.io/issues/15053

It now looks like it has been fixed. They're visible now.

This is the background worker for the new source viewer falling behind. It has to process the newly published .crate file into a seekable zip archive. Nothing is broken, it usually just lags an hour or so under load.