Clearly the absence of any reply indicates that it can't be done. Bizarre though - SSDT clearly is exporting the schema AND data (which is supposed to be the BACPAC) but it only provides the DACPAC file type. Odd.

There has to be an answer.

I have managed to get my on-premise database to Azure but not via SSDT (a tool which was supposed to be able to do it).

In the end, I just downloaded Management Studio for 2016, connected to my SQL 2012 instance & chose the usual Export Data Tier Application to generate a BACPAC. It created the BACPAC without error! After a solid week struggling, I just needed the latest incarnation of Management Studio!

Cheers