Cannot change VTX settings. Page does not seem to respond.

I'll start this by saying I'm running Betaflight 4.5RC2. If the answer here is 'we don't support it 'till it's released', that's fine with me.

The VTX tab is simply not editable. It opens and stays with band at U, channel 0 etc. etc.
I *can* change channels, bands, etc. using the OSD in goggles with stick controls so SmartAudio control is working. This change is not reflected in the tab on the radio.
The option to redownload the VTX table does work (I have checked the .lua on the SD card and it has correctly pulled the values)
I have tried setting a specific frequency on the Betaflight configurator as I saw that suggested somewhere. No difference.

Other tabs are editable and can be saved (rates for example).

What hardware / software you are using:

Taranis X9D+ running 2.3.12
Betaflight 4.5RC2 on a CLRacingF4S board connected to an X4R-SB running SBUS and a TBS Unify Race Pro HV with SmartAudio

Reproduce the VTX tab behavior on the listed Taranis X9D+ and Betaflight setup, then compare the tab with SmartAudio changes made through the goggles' OSD. Inspect the Lua script on the SD card and the VTX table behavior; done means VTX settings can be edited in the tab, saved, and reflected on the transmitter.

Written by the indexing model from the issue text.