I’m having the same problem. Xcode updated, Safari updated and also tried the Safari Technology Preview!
The same problem here.
Sometimes (with my iPad pro 10.5) it helps to power down the tablet and power it on whilst being connected to the Mac via USB. The same procedure does not do the trick with my iPhone Xs. The phone will show up in the dev menu after booting only to disappear again after unlocking the phone and the SIM.
(Safari 13.0.1 / iOS 13.1.1 / iPadOS 13.1.1)
I'm having the same issue, Been through several, rounds of revoking then reapplying the "Trust this device" options, weirdly, it would allow me to see Web Inspector Content up to the point I would enter my passcode on my phone and then, as soon as I did my device would disappear from the develop menu.
I don't have solid, reproducable proof yet but I saw in some other thread that theres an issue with the Charge status. So if your phone is at 100% charge (which being connected via the usb cable is quite likely) you won't see it listed in the Develop menu, but this morning with my phone at 46% charge there it was.
That said the experience is still very erratic so it might not be as simple as that.
Hi have the same issue, really annoying, inpact my workflow in a very bad way, any clue ?
So this was the thread that made the connection to the Battery charge status.
What worked for me was:
1) Let your phone run down to 50% charge (Arbitary %, iOS has some kind of 'smart charge' around 80% setting the impact of which I have no idea about.)
2) Connect your phone via the usb cable and load up any webpage on iOS Safari
3) Go to the develop menu in MacOS Safari, hopefully you'll see your phone listed or a prompt to allow development
4) Under your phone's name there should be an option to "Connect via Network", tick that option
Until I selected the connect via Network option my phone would disappear again when it reached 100% charge but now it's been available for a couple of days straight now.
Also, out of sheer frustration I deleted xCode, can't say if that had any impact but the extra 14GB of disk space and the crunching sound of the trashcan as it emptied did make me feel a bit better for 15 minutes.
Thanks so much, your "connect via Network" solution did the trick for me after hours of frustration!