I've managed to reproduce this and find a workaround.
First, please ensure that you've modified your config.xml to include the necessary permissions and features.
BBM
<rim:permissions>
...
<rim:permit>bbm_connect</rim:permit>
...
</rim:permissions>
<feature id="blackberry.bbm.platform" />
Payment
<feature id="blackberry.payment" />
Second, there seems to be an issue stemming from minifying the scripts. When minified, I noticed Web Inspector was logging the following error:
blackberry.bh.platform is undefined
The API should be blackberry.bbm.platform, but the minification process appears to be changing the API signature to something that does not actually exist.
When I opted to not minify the scripts, the API executed as blackberry.bbm.platform and proceeded to function.
No changes were made to the CAPX file or plugin files.
Can you give this a shot?