Aha! Yeah, I’m able to replicate the issue now. That does indeed seem like a bug, so I’ll report that and follow up here when it’s resolved.
Edit: I just gave this a bit more thought and I think there might be something else at play. The paged attribute isn’t a query parameter, so it probably needs to be added when loop is run, not added to the query variable. In other words, the template should be
<Set query=my_query type=post />
<Loop query=my_query paged=3>
...
and not
<Set query=my_query type=post paged=3 />
<Loop query=my_query>
Eliot explained the differents between query parameters and regular attributes here and it’s also mentioned in the docs here. That being said, when I try that the pagination still doesn’t work so I think there’s still a bug here related to paginating query variables. I’ll have someone look into this and also confirm where the paged attribute should be placed.