I'm finding that auto generation tends to leave some areas unsupported that still need support (even with 1mm res), so I'm needing to customize most of the time to clean up and add supports to missing spots. On some models, I need to check and add supports in areas that are fairly closed off and hard to see into. In that case I tried to go into Cross section mode, and slice the bottom so that I can cleanly see all the bottom surfaces to check and edit as necessary, however supports cannot be placed if part of the support intersects the cross section. The cursor placing the support is on a visible part of the mesh, but if the other end of that support is cut off by the intersection, it does not place it.
This could just be a bug, but in case not, please add the ability to do so.