Hreflang missing a return link
What it means
These pages declare an hreflang alternate that does not point back at them. Hreflang must be reciprocal: an unconfirmed annotation is ignored, so the whole cluster stops working.
How to fix it
Every page in a language group must list every page in that group, including itself. If A declares B, then B must declare A. Generate the block from one shared mapping rather than writing it per page, and remember to include the entry that points to the page itself and an x-default where you have one.
Finding it in CrawlStat
After a crawl, open Issues and pick Hreflang missing a return link. Click Show all in Pages to filter the Pages table to the affected pages, or Export affected to hand the list to whoever owns the fix. Audit ID: hreflang_missing_return.