RE: Ironing not applied on top of first part of a two-materials print on the Prusa XL
Yes, this is the right file.
RE: Ironing not applied on top of first part of a two-materials print on the Prusa XL
Its quite simple why its not ironing. Ironing only applies to top surfaces. Your bottom object is only a single layer thick so its just Solid Infill (purple in colour on the type key). As that is what the bottom layer is printed as. It needs to be actual top fill (Red) for ironing to be applied.
You could argue that its the top layer so why isn't it treating it as top. Well First layer settings have priority over that as getting it to stick to the print bed is more important. Also I'm not sure how practical it is to iron a first layer anyway, for me they are always smooth if my live z distance is set correctly. So no ironing required.
Either make that bottom part thicker to print as 2 layers or change your layer heights such that the first layer and your normal other layers adds up to match the 0.28mm height you have. Something like setting the first layer height to 0.1 for example allows it to have 2 layers.
RE: Ironing not applied on top of first part of a two-materials print on the Prusa XL
OK, thank you for the explanation @Neophyl!