I was making some changes to a site, and was using BB on the front end to edit a post.
When I returned to the admin (open in a different tab page in the customizer) I noticed this error at the top of the screen. No adverse effects noted, and it did not return after I left the customizer.
I had previously been making changes in the customizer to fonts/sizes etc…
Regards, Dave
ps - latest version of BB and BBT
Warning: Invalid argument supplied for foreach() in /home/bpbitume/public_html/wp-content/themes/bb-theme/classes/class-fl-customizer.php on line 699