64 bit audio engine different

Hi peeps
I've had this slight irritation for a while now, since going 64bit in fact.
Using BFD 2 (my go to drums) in 64 bit sonar, bringing up the BFD screen
kills the audio engine, as soon as I minimize it the audio engine switches back on.
I've been doing a few investigations and have noticed that whilst session drummer 3 doesn't do this, session drummer 2 does.  Addictive drums doesn't do it but
Antares Moog Modular does and I'm sure I'll find others too but that's enough for now. I'm sure they all do it for the same reason.  What ever that is?

Neither session drummer 2 nor BFD 2 or any other instruments behave this
way in 32bit sonar so it's definitely a 64bit problem.

Anyone have any suggestions as to why this might be?
Thought it might be a bitbridge thing but it happens with jbridge too.
Steve

Yes Paul
Tried it on and off and it still does it.
It is weird, like I said in my op, I could go through all my other VSTi's and see which ones do and which ones don't but I quite certain that whatever the cure
(if there is one) will work for all of them.
I was wondering if other BFD 2 users shared my experience but if you have sonar x1a or 8.5 64bit in a 64bit os you could see if session drummer 2 does the same thing?

Steve

Thanks Pwal
I really ought to list the steps I have taken in my investigations as checking and unchecking the 64 bit precision engine and "share divers with other programs" were the first 2 things I did. It's interesting that session drummer 2 behaves this way but not session drummer 3. I thought maybe it was a BFD 2 thing at first.
Have you tried it for your self to see if it's not just me?

Steve