Hi Ed,
I think it is the question of how strong the interference is.
In the beginning of november I joined a DX Camp on a 760 m high mountain with a huge FM transmitter tower on top.
This time - no such problem when using the BPF. But last time in march - without the BPF - I realized there quite often FM interference which made me change to the Apache Labs Hermes receiver board.
Maybe if you compare the size and housing of your TVI filter with the tiny filter on the BPF board you know why.
Regards, Frank