Hreflang alternate as single-hop 301 - is this actually a problem?

[scottclark]

First, this is not a question about whether 301 redirects pass page rank.

My question is that if your hreflang alternative page URL is a 301 redirect*, are there any downsides.  In all cases with our situation, the 301 redirect is single-hop and working.

Tools, such as SEMRush seem to flag this as a non-canonical hreflang error, but I'm not able to find any cases where Google has suggested a redirecting hreflang is a problem.

I'd appreciate any information on this issue before we invest extra time on a large international site.

*In Drupal, there are scenarios where it's all but impossible to avoid having a 301 redirect in your hreflang alternate URL without significant custom work.