Inserting/upserting a document with long-term expire duration immediately deletes the document

Whenever I try to insert/upsert a document, with a long-term expire duration (e.g. 1440h), the document immediately disappears from the Bucket.

E.g.

conn.Collection.Insert(documentId, myStruct, &gocb.UpsertOptions{Expiry: 1440*time.Hour})

// or 

conn.Collection.Upsert(documentId, myStruct, &gocb.UpsertOptions{Expiry: 1440*time.Hour})

When this code runs, I cannot find the document in the bucket. I tried also upgrading to CB community 6.5.1, and there I could see an "Error, document not found" message in the CB web UI, near the document id.

I can successfully upsert documents with short expire, e.g. 5 seconds or 1 hour.

I can safely reproduce the issue with a simple test suite, so I am assuming the problem is not random. When the test runs, it upserts with 1440h duration, then immediately gets, and the document does not exist.