So here I am a year later, still encountering and seeking help with this problem. Fwiw I pointed an AI at the problem, and it said:
The issue you’re facing, where the “Low Flow Trigger” is “Disabled due to Manually Calibrated Drip Zone” even after recalibration, appears to be a known limitation or behavior for drip zones that have been manually calibrated. The system might categorize these zones differently, preventing the automatic low-flow trigger from being enabled.
While I don’t blindly trust AIs, they are pretty good at digesting and consolidating information from various sources like this Forum, Reddit, etc. So it seems like it’s a known bug. Kinda sad. I’m a software engineer and I can’t imagine it’s that hard to fix.