Controller not showing in Available DFU Devices menu

Hello!
I have a FBL2360TE Controller. It is working fine and I am able to use it with Roborun +.
When I try to update firmware via USB, the DFU Loader opens and the controller STAT starts blinking red and green. However the controller is not listed in the Available DFU Devices drop down menu,

I want to upgrade the firmware. Can someone please help me solve this?

Also, Is it possible to load the firmware of FIM on an FBL controller? Has anyone here tried this?

Thanks