iViewer 5 V5.0.8 Build 410
GuiDesigner V2.7.10.303
Project properties: iPhone X , 812x375
File -> Export -> Encrypted Project Archive (or Project Archive) : only images with @2x are added to project file
Also, I cannot see in Remote Debugging Monitor if @2x or @3x images are been loaded. It only shows normal images. Despite of that, I can guarantee that the images with @3x are been transferred to iPhone via guiDesigner (my @3x images have different color background and I could see them in iPhone 11 Pro)