I'll disclose I am not an expert on NSX-V, my knowledge is of NSX-T, however, by default an NSX-T backed segment will drop PXE traffic. This is because under the Segment Security Profile Server Block is enabled.
Networking > Segments > Profiles you'll find it there. Create a new one and disable Server Block. Add that new profile to the NSX segment and you should get PXE back. I've come across the same thing in my experience.
https://docs.vmware.com/en/VMware-NSX-T-Data-Center/3.2/administration/GUID-C34CCED2-128E-49A6-98CE-...
