The point was made that it wasn't Simmons' responsibility to increase his trade value, and that the Sixers should find the best possible trade and execute it now, rather than wait for a strong start to the season to increase his value.
Why hasn't Simmons been traded yet?
The simple answer? Because Damian Lillard and Bradley Beal aren't available yet.
Until there's any movement there -- or another team comes in with a huge offer for Simmons separately -- it seems likely Simmons will remain on Philadelphia's roster for the foreseeable future.
Expect the NBA to step in if Simmons does not report and the 76ers do not penalize him financially with a suspension. The last thing the league can afford is a precedent of players under contract not reporting for training camp.