Hi, I wrote the hello-rust template, and can confirm it did work at some point, but no longer does now that I check it.
At a guess, it would seem Glitch no longer allows access to the location cargo was using to store files, or else Glitch’s version of cargo has been updated and has breaking changes to the way it stores files that aren’t compatible with Glitch.
It’s difficult to say where the issue lies, without insight from the Glitch team.