Hi @label1 ,
Could you add some Screenshots please? I, for one, don’t understand what is happening from your dscription.
Especially this part: “…stlll won’t show the parts of my mesh if I switch to front view. If I deactivate “overlay > Extras”, it shows the mesh in front view as it should, […]. But as soon as I switch ithe overlay Extra on again, that part of the mesh disappears…” sounds extremely weird.
Maybe it’s a Bug; after all it’s 4.0 (first Release after major changes), you could try Openeing the file in 4.2, or Appending the Model in 3.6…
