Be careful sraying fabreeze or anything else on the flysheet, it might affect the waterproofing .
maybe if you soak it all with a hose and let it dry in the sun , it might smell a bit better .
is the breckenrdge an inner first pitch ? too big to wash the inner in machine , then , Id wash the inner in the bath, or a paddling pool , rinse well and either dry on the line or pitch the inner to dry .
if no visible signs of mould, it could be the groundsheet is holding the damp smell too.
It's only the inner tent that smells. also didn't spray it on the fabric. sprayed it inside. I've got a gelert candiz 4+2 as my other tent was way too big for me to just go camping in.