Is the Contextcapture Editor some kind of joke? We are unable to edit any real models using it. If the model for retouching DGN/OBJ is quite large like 200-400MB then the Contextcapture Editor can't handle it as the mesh is very slow to display and no snap is possible. Also even if model is edited then importing it back it introduces more issues in 3mx model. It seems that for some reason CC Editor divides mesh in lot of segments when opening and after retouch Contextcapture can't merge all meshes correctly. Editing works correctly only for very small models which opens as one mesh.
There are no issues if using third party software (Meshlab or Meshmixer) to touchup the mesh but not with CC Editor.
Grad a demo license of 3DReshaper .. let me know how you go. Pretty sure it can ingest OBJ .. can certainly put it out. Not cheap mind you.
How big are the tiles you are trying to edit? Edit smaller/less tiles?
3DReshaper has lots of other cool things too .. might be handy - eg ground extract .. reporting .. stockpile volumes .. depending on whatever else you are doing.