TWS previously displayed a Rebate Rate value associated with a feature that is no longer supported. Effective with release 10.19, Rebate Rate is no longer available in TWS. The Fee Rate is still available to display for clients who pre-borrow shares to short.
Ongoing updates to the API require clients that are using a version below 36 to upgrade to avoid unsupported attributes. One example is the Outside RTH feature. The paradigm that once included two attributes - rthOnly and triggerOutsideRth - is obsolete and may cause issues. This feature is now supported via a single OutsideRTH attribute and requires an API version of 36 or higher.