I installed Gravity Forms on a site where I already had the debug bar, and on every Gravity Forms admin page the debug bar appeared broken.
Turns out that Gravity Forms has a thing it calls "no conflict mode" which it enables by default. Basically they have a whitelist of scripts and styles and unenqueue all others on their admin pages to try to avoid conflicts. I opened a ticket with them to add debug bar scripts to the whitelist, but they do offer a couple filters to allow a plugin to add to the whitelists themselves:
gform_noconflict_scripts and gform_noconflict_styles
If this is on Github or if you accept patches somewhere, let me know.