Data missing in export

Hi together,
we are migrating from one to another self hosted GitLab server instance. When I was migrating some projects, we encountered that several issue links in the issue description were broken. Moreover linked (or related) issues were missing.

The first topic might be a bug whereas I am not sure about the second topic. Are issue relations excluded from the export? I tried to find them in the issue.ndjson in the export tgz file but all linking issue was missing on that stage.

Does anyone has experience with the export feature?


I forgot: We are using GitLab 13.8.2 on our old and 13.8.4 on the new server instance.