Ok, I think I found something.
To the risk of repeating myself, I’m on X-Box so someone would have to verify if it’s the same on PC.
So I tested the 2x2 raider windmill plot by doing the same (starting with a non industry plot, change it to industry, select the power one). It worked fine.
I went back to interior plots, took a plot, changed to industrial and then selected another power plot. The Vault Tec Tools plot had the same issue. It creates power but the plot indicates that it should have power going to it anyway. I then changed it to RS Turbines and it was working perfectly fine, indicating the power supplied and not that it required 1. Downloaded Whisper’s power plots (the only other interior power plot on Xbox) and they are working fine. And I can change from one working power plot (let’s say Whisper) to a non working one (let’s say BRM) back and forth and it stays the same, the one working will work next time and the non working one will keep not working every time.
And to be thorough I tried building an industrial of any kind that required power (wood production in this case) and then changed to the s BMR power plot and it worked perfectly fine, no wrong indication of need for power.
Here is the kicker: the Vault Tec plot and the blood moon raider power plot both Require to connect via wire. The Whisper and RS plots don’t. So from what I can see this is an issue that happens only on interior power plots that need to connect via wire and only if they started as a different type of plot (ex: residential) and then changed to industrial.