Hello!
Here is the way to do it.
1. Make a trigger that sets a variable, e.g. bet_cntr to 0. The scope should be Global, and the trigger should run "one time only".
2. In the betting trigger, add an action that sets bet_cntr to bet_cntr+1. Also add this condition to the betting trigger:
Selection's Trigger Expression bet_cntr is equal to 0
3. Make another trigger with an action "set user variable bet_cntr to bet_cntr-1". Apply the trigger to settled markets, and in the condition of this trigger add:
Trigger {name of the betting trigger} number of runs is greater than 0.
The idea behind this is to count each time when you place a bet in a market, and then decrement the counter after the market is settled. If the counter is greater than 0, this means that some event is still not settled, so the trigger won't bet.