CPU pinning helps host/guest to use certain CPUs only. That does not mean, they take full control of these CPUs/Cores. I had the same issue and managed to fix it by using CPU isolation. This, completely removes access from host to certain CPU Cores, which are then used by your guest. The process is initiated by a script on VM start, and when you shutdown, it reverts the process, and they are available again to the host.
Take a look in this thread for @anon86748826 solution that worked for me: