This might not be the same cause for your original issue but I ran into a similar problem in that overrideAttrs would silently just keep the original package. According to a different thread, if the sha256 hash matches a hash from nixpkgs, it would just use the original version without checking that the rev has changed.
This was surprising, as I’ve previously used this method to get the actual hash from the new version in other contexts, so I’m not sure what was different from this method.
My dumb workaround was to change one char in the hash or there’s the nix-prefetch-git workaround.