Apologies if I am stating the obvious (I am quite new to the M5Stack arena). I had the same problem as you (in fact, I still cant get the web integration to work), but I did manage to get the Windows UIFlow install to work as follows:
(1) Installed the CP210x_VCP_Windows
(2) Installed the M5 Burner software for Windows
(3) Installed UIFlow for Windows
I then used the M5 Burner software to download the v1.5.2 firmware for the M5Stack Fire which has a 'Setting' option of 'Switch Mode' in it (when installed/Burnt). Once the Switch Mode was set to 'USB Mode' , my M5Stack Fire then connected to the windows version of UIFlow with absolutely no problems (I also changed the VER option to BETA in UIFlow for Windows which sets the UIFlow to version 1.5.2 as a just in case).
So far (fingrers crossed) it has connected everytime.
Please note, (not wanting to state the obvious but I am not sure what version of the firmware you have) .... but the 'menuisation' on the M5Stack Fire only appears when you download the v1.5.2 firmware (unless I was installing previous versions of the firmware incorrectly).
Thinking about it, maybe if I set my switch mode to 'Internet Mode' that will start working for me ......
hope it helps,