The red on top (instead of on the bottom) in solid view means that the normals of your model are reversed. It should by itself not influence slicing (because CuraEngine does not use the normals). If you install the Mesh Tools plugin from the Marketplace, it will add a function that will let you fix the normals. It will also tell you when there's a problem with your mesh.
Recommended Posts
Smithy 1,141
I guess you have a problem with your STL file (not watertight), because it is also strange that you have this red part in the solid view, which normally indicates an overhang.
Check the x-ray view in Cura if you see some red parts there, if so, then your model has some defects.
Link to post
Share on other sites