Hello,
Just be aware that TWS API has an issue regarding delayed market data requests (when you don't have real time subscriptions for the specificied instruments)
It was working fine until TWS 9.73 but it doesn't work as expected anymore.
Here are 2 snapshots, the first one has been generated using TWS 9.81 (where we don't received delayed market data / no bid & ask received for most options)
Whereas it works fine using TWS 9.73 (second snapshot)
Similiar tests have been conducted by different users on various workstations with similar behavior.
