Betas 6 & 7 have broken personal hotspot for me.
I have to open the personal hotspot section in the settings app on my phone, leave the screen on and then it will show up as a WiFi network on my MBP.
Nothing has changed apart from the update and it worked fine up to Beta 5.
I have utilized my cellular iPP as a personal hotspot through the lightning cable a number of times through the last three versions of Beta macOS and have not encountered any issues.