I presume this is the same system using both versions of cpuminer-opt.
Of course I'm seeing these results on the same system.
I've reviewed the changes I made for 64 CPU support and they should only have an effect when
there are more than 64 vcores. It's as simple as if num_cpus > 64 do something different else
do as usual.
The issue must be somewhere in cpu-miner.c.
If we copy cpu-miner.c from v3.7.5.tar.gz to 3.7.6 and compile it, all 48 CPUs are used.
If we copy cpu-miner.c from v3.7.6.tar.gz to 3.7.5 and compile it, only 32 CPUs are used.