Power Manager Using Wrong Custom Settings

Win11 

Using the Custom option in Power Manager, I've set the point where the battery is to stop charging at 90%.

Initially it maintains the setting but after successive reboots, it now stops at 71%.

I've tried other settings and it always reverts to ~ 20% less.

However,  the Custom Power Manager settings remain as I set them.

Also, I am unable to set the Starting point as it cannot be changed from 50%.