[Replacement pattern with {...} won't get replaced]

Hi there,

 

I have some strange behavior when slicing, which is probably just because I don't see my mistake. I'm using some custom start code. One of the lines contain for example 

M140 S{material_bed_temperature_layer_0}

  

My expectaion would be to see something like "M140 S60" in the sliced G-Code file, but what I see is for example this:

 

;FLAVOR:Marlin
M73 P0
M117 Time Left 0h40m33s
;TIME:2433
;Filament used: 1.01777m
;Layer height: 0.1
;MINX:79.625
;MINY:74.192
;MINZ:0.1
;MAXX:150.375
;MAXY:144.942
;MAXZ:27.65
;POSTPROCESSED
;Generated with Cura_SteamEngine 4.10.0
M82 ;absolute extrusion mode
; Ender 3 Start G-Code
M501                                                                   ; Standardwerte laden
M82                                                                      ; absolute Extrusion
M117 Vorbereiten                                                         ; Info am LCD
M107                                                                   ; Bauteil-Lüfter aus
M140 S{material_bed_temperature_layer_0}                   ; Bett heizen
M104 S180                                                                        ; Düse vorwärmen

 

There is no M140 from Cura before my start code. That basically indicates that Cura recognized that I have own temperture settings in my start code. Fine!
But why do I still see the variable name instead of the value?

 

And an additional question: is there a posibility to make an easy calculation in custom start code? Somthing like "M140 S{material_bed_temperature_layer_0} + 15.0" ?

Thanks!