I use Tiffen filters in conjunction with the the BMPCC, and yes they are lousy with IR pollution. However, I stack them with Hoya IR/UV cut filter and it seems to get rid of the brownish/red tint. I've tried different stacking orders, but it didn't seem like they made a difference, the IR pollution seem to be cut regardless. Not sure what IR filter you are using, but maybe it's not enough to block the IR pollution. Just Tiffen variable filter. Tiffen stacked on top of the Hoya IR/UV cut. ND's are mysterious on the BMPCC because sometimes they cause a ton of pollution and sometimes they don't. For me the Hoya seems to mitigate it decently.