“Nulle part” is a fixed adverbial expression; no ‘agreement’. Can you reference where you came across nulle parte.?  If on this site, I am sure they would like the opportunity to correct what was possibly/likely a typo https://www.larousse.fr/dictionnaires/francais/nulle_part/55240

I only know nulle part (nowhere).

The word parte I recognize not as a noun but as subjunctive present tense, 1st and 3rd person singular of the verb partir.