Well... Fair enough, then.
I'll add it to my impressively short list of design flaws in Factorio.

Hmm. Fluid mixing. So, 'F.'
Let's see... Yes, it'll slot in right here between 'Circuit logistics: One Computer = One Abacus' and 'Trains: My god what have you done to trains.'

Thank you for that.
I stared at it for a while thinking I had to be missing something before posting it as a bug. And I was!
That said, while maybe I wouldn't call this a Bug with a capital-B, it's certainly some color and flavor of "design issue."

I figure I got to this fluid-locked state after ...

Adding save file and log.

In 1.1.32 (build 58364, win64)

I have a light-oil-cracking chemical plant with logic. If light oil > petro gas 'L'=1... if 'L'==1, turn on light-oil cracking.
After quite a while with just the one plant, I tried to add a second next to it. But the petro gas output won't connect to any other petro ...