It won’t appear by itself until you connect a compatible phone and it starts AA or CP.
So, if you haven’t connected a phone, do so.
If you have, follow the previous “guide”.
Just keep in mind that guide references the once latest 3.0 build 20204… since your opening message was vague and just said you upgraded to 3.0, make sure to go back to your current build once you are done… You should already have the file since you upgraded it…
Are you using a good quality iPhone USB cable?
Some of the cheaper ones do not have all the data pins wired, just the charge pins.
You can also have a cable where one of the data wires is broken.
What is the part number and source of the USB module?