wow… and you are sure it was former enabled ? You can not enable core isolation if there are “incompatible” drivers.
If it was enabled , then may be these super OS not recheck the preconditions if you install some what new . But now, as you try to enable it, it check your system ( you can see the list of which drivers it detects ).
At least… as I mentioned… dont worry about. I assume a lot, realy a lot of users have that disabled as exact same driver thing ( or simple Virt.Support in BIOS disabled ). If windows 11 enabled it and not recheck the preconditions , I will no longer wonder about some problems ( but , I not wonder in general about that beta OS 
).