Omar-Os Rishav's team is continuing to look into this, however, there is not much new information to share. It seems like there's something happening in relation the specific devices that you've attempted this on, as most other users are now reportedly able to import data from Firefox just fine. As tomscharbach mentioned a while back, opening a support ticket will likely be best, as our support agents can offer individualized troubleshooting. And if you haven't yet, we also recommend submitting detailed feedback and diagnostics through the browser (Shift+Alt+I, or "..." menu > Help and feedback > Send feedback.)
And while we love to see your eagerness for info both here on the forums and our other social sites, our moderators wanted to remind you that comments on community threads should be constructive, polite, and substantive. We appreciate your help in keeping our community positive and vibrant!
Fawkes (they/them)
Program Manager & Community Manager - Microsoft Edge