First, forget about XP reinstall - you should never do this for any plugin or troubles. Actually you can move the whole XP folder anywhere for backup, and copy it back .
- De_Ice_Pressure - it's always shows current pressure value 0, and you can see that the related virtual gauge is in zero position.
Maybe some conditions are needed to make this custom dataref to show pressure in this model (when you switch the pneumatic de-icing system ON and ice is present?)
- Prop_Heat_Amps - It shows 0 Amps when Prop heat is OFF, and some amps value when ON (and XP is not in pause mode)
These two parameters are the custom, they don't have a standard XPlane datarefs. So they are mapped to (new custom) Laminar B58 datarefs and works only for this plane.
As for fuel parameters - they use the standard XP datarefs, but for this Laminar B58 they use replacement datarefs for this plane. Only if for some reason these custom datarefs are not registered in XP when B58 starts, the plugin can't read them.
Again, what is your B58 model - does it the "default" XP11 Laminar Baron?