Fixed currency exchange rate does not overrule live rate

ERPNext: v11.1.71 (version-11)
Frappe Framework: v11.1.63 (version-11)

I have set a fixed currency exchange rate for USD/CNY (0.141284505) conversion.

I expect this to be applied on any document created on/after the applicable date (Jul 1st 2020 in my example here)

however when I create a new SO (date 5 Jul 2020, which is after the date of the fixed rate shown above) This fixed rate 0.141284505 is not applied to that SO but a different rate 0.14152 (which must be the live rate generated from

can anyone guide me on what I am doing wrong here?

My understanding is that you need 1 FX per day.

Interesting. If that is so article in the manual is sparing us this little but critical detail

Let us know if you find out more about it. I vaguely remember that was the case. Thanks

Have you had any luck getting this to work? I cannot set a fixed exchange rate no matter what I do. Both on v11 and v12.

Tried to change stale days checked unchecked. but will not update in neither sales order/invoice nor delivery note.