IANAL. Do not take anything I say as legal advice.
I know of no adverse action for someone answering "no" and then being denied because the answer should have been "yes"--other than the denial of the firearm transfer, which is going to happen anyway (without the NICS check being done) if you answer "yes."
Answer the question "to the best of your knowledge." If, as far a you know, the TPO was a holding measure while the details are sorted out and that, there being no basis, no real PO was put in place, then honestly answer the question according to your knowledge. If you are denied, you can appeal by contacting the FBI, and find out why you were denied. If you were denied because of a TPO that turned out to have no basis in fact, then I'd retain a lawyer, for two reasons: (1) to get the denial overturned and prevented in the future and (2) to sue the b**** who got a baseless TPO against you out of spite. You'll be able to prove that you were damaged by her actions, making her liable (if the statute of limitations on her actions has not run out).
Anyway, this should give you a few things to discuss with your lawyer should you get denied. He'll be able to give you legal advice. I can't.
Of course, all of this is assuming that the TPO was baseless. Some TPOs with a solid foundation still never become POs. If there was a basis for the TPO, forget I said anything.