Update QTreeView when I change column count in my custom ShotgunModel (from tk-framework-shotgunutils) hierarchical model

I have setup a custom model inherited from ShotgunModel from tk-framework-shotgunutils. Connected it to a QTreeView with a proxymodel in between. Now when I change column count of my model, the tree view doesn’t update the headers particularly when I remove a column. The header for the removed column remains there. It doesn’t show any data, but it remains there.

I’ve tried layoutChanged, headerDataChanged signals and beginResetModel and endResetModel calls too. But nothing works. Does anyone have any idea about this?