I had this and reported it somewhere before (Missing extrusion surfaces when mirroring). What I was told to do, and worked for me, was to select the offending object, “explode” it, and then immediately “join” it
I had this and reported it somewhere before (Missing extrusion surfaces when mirroring). What I was told to do, and worked for me, was to select the offending object, “explode” it, and then immediately “join” it