I’ve also got the same problem. I’ve worked with Appsheet charts a lot and have never realised that you actually can’t have a chart with time (or date, or datetime) as the x-axis!
Surely this is an omission!
If I want to chart [Blood Pressure] against [DateTime] where [Blood Pressure] is Decimal and [DateTime] is a Datetime then the best I can do is to have [DateTime] as the label.
But this is not actually what @Dave_Inman or myself were really after. It displays the points in a sequence, but if you miss a week then this gap will not be reflected in the chart because it’s just a sequence of dots with lables.
The behaviour that @Dave_Inman or myself were really after is a real plot of how a parameter varies with time.
Try it. It’s impossible.