So sorry for the frustration and lost time the issue caused you.
There is indeed a bug in the new Balsamiq Wireframes editor that prevents some symbol libraries to show up in the UI Library. We’re working on fixing it already.
Regarding Balsamiq Wireframes for Google Drive, the new version is not officially released, yet.
We have several products that are currently in private beta (with some users trying it out) but Balsamiq Wireframes for Google Drive is not one of them. We figured out how you managed to install the new Balsamiq Wireframes and would like to welcome you as our first official user of Balsamiq Wireframes for Google Drive!
Sorry again for the snag! We’ll do our best to help.