I had similar issue, the computer model was getting to the WinPE Environment but the Network Adapter was not recognized. as Jason mentioned , create Driver Binding for the WinPE image and the Computer model. On my case the Driver that was “Driver Bound” was from the Dell WinPE Driver Pack A30 - for some reason, it causes issues.
So I’ve uploaded the Network driver from the specific Driver pack model , bound it to the specific model and the created Binding Grid as before and edited the “Current Manual Binding” with the new Driver.
Of course , after assigning the Binding, make sure that the Update Driver Manifest action complete successfully and on the Health checks there are no sync errors - after that you can PXE again - https://help.hcltechsw.com/bigfix/10.0/lifecycle/Lifecycle/OSD_Users_Guide/c_managing_bindings.html