> However, if I start with the .config which workd, and "make xconfig"
> and select "Supported processor types" under "Processor type and
> features" and then unselect "Support Intel Pprocessors" (I have a
> Ryzen) and save the config, it decreases the size of .config from 169K
> to under 13K, losing almost every setting in the file.
>

Checking my systems, .config is 131k (AMD system, so CONFIG_CPU_SUP_INTEL
is not set) and an Intel system is 116k.

Try following the same procedure using make menuconfig instead of make
xconfig and see what happens.