Here is another more recent example:
New issue, with two labels: css-overflow-4, css-scrollbars-1
Only the first label was added to the Bridgy Publish POSSE copy:
Is this the same problem? I thought perhaps with the switch from GraphQL to the GitHub v3 API a few weeks (months?) ago, this might have been fixed at the same time.
Whatever the cause is, some labels are still not getting through via publish.