I don't write very well- please accept my apology for this.
Here is an example:
Suppose the current bid for CME Crude Oil is $94.00. Suppose you are long One contract, entered as a LMT-STP order, (say purchased at $94.05) with a Stop-Loss of $93.95, entered as a STP (to be executed as a MKT order by the system).
Suppose the price of Crude Oil "air gaps" to $93.90.
Your stop will never execute. It didn't execute thru the gap (which is understandable), but it won't execute now, even though the market price is 5 cents below your stop-loss. On TWS, you still see your order's stop-loss at $93.95, still "ready" to execute.
IB admits this flaw, and now disclaims liability over this. It's absurd.