Ana

The asymmetry is the answer. Only one direction has special handling and everyone assumes both do.

Two machines behaving differently with the same setup is almost always the version difference the fourth comment mentions, and it is genuinely miserable to search because both behaviours are documented as correct, for different versions.

Check the networking mode on both before comparing anything else. Once you know they are in different modes, every other difference explains itself.

Using the address the distro already knows rather than localhost is the fix that survives version changes, which is why I would reach for it first even when localhost happens to work.