All settings and input fields are empty when 'Increase Contrast' is on.
Take a look at these screenshots:
Form fields and values are visible, as expected:
No values are visible throughout the entire application, except the currently selected field:
As you can see the difference is that "Increase contrast" in checked in the Accessibility controls.
I use "Increase contrast" and other Accessibility options in macOS and iOS because I've always had stereoscopic vision and since "flat design" (which is almost exclusively monoscopic) became popular a few years ago it's been much more difficult for me to understand what I'm looking at on a screen. Then when "dark mode" became popular the problem was compounded.
The "increase contrast" option is kind of a like a "material design" auto pilot that typically ads borders to forms and buttons to help simulate depth so that people like myself can tell the difference between things more easily without having to pause and analyze the screen or guess and check.
Screenflow has enough contrast normally that I don't need this option specifically for it, but I'd prefer to keep it on rather than having to disable and re-enable as I switch around.
P.S. My wild guess is that the developers have some old code from before Screenflow switched to "dark mode" that originally increased contrast my darkening fonts from grey to black - as expected for Accessibility mode - but in the newer versions were not updated and so instead of going from "dark white" to "bright white" as expected, it keeps the old behavior by mistake... and becomes invisible.