There are two issues here. Not sure if they should be two tickets or not.
The attached projects has a FilteringUIContext with an Accordian control bound to a DataTable. The accordian is in a collapsed state.
There is a filter applied on both of the columns.
If you run the project, you notice
1. that the blue triangle filter indictator is not visible on Col1 until you expand. Once you collapse, at that time the indicator correctly remains.
2. that there is no indicator for the boolean field for whether or not there is a selection. This also prevents the user from clearing that specific filter.
The first behavior you are observing occurs since data bindings are initialized on creating the control's handle. That is why if you move your code from the Form1 constructor to the OnLoad method, everything will start operating properly.
Regarding the second case, we agree that the current behavior can be improved. That is why I have created a new FilteringUIContext - There is no indication for an applied filter and there is no way to re-set the current filter for a Boolean field ticket and forwarded it to our R&D team for further investigation. We will update that thread once we have results.