that feature is still in the beta version, not yet in the release version,

Have you tested this feature ? Any feedback about it's maturity ?

You might enjoy the blog for this: https://thunderbird.topicbox.com/groups/android-planning

Hello David,

I checked the blog, but no thread or discussion regarding the topic of generating a QR code on Desktop version to scan and import accounts on the newly release Mobile / Android version of Thunderbird.

This is still new, so one possibility is to test it yourself and contribute your findings to that blog.