I had tried various methods as suggested on Microsoft Community, but was unable to solve above issue for past few months. I decided to Reset, while keeping personal data. After Reset today, I am able to toggle On/Off for; Core Isolation > Memory Integrity. Also while checking Security Processor, I am able to see TPM.
I feel, if similar issue occur again during future update, maybe I will wait for next major update, so as not to waste so much time on such issue.
Also, I was informed by a computer retailer technician that they frequently encountered Windows 11 update errors, on their dept's (branded) computer. As their computer has no data to backup, they frequently perform Clean Installation at least "once a month", followed by Windows 11 update, to overcome Windows update errors.
By the way, my PC as following:
Asus H610 motherboard
Intel I5-12400 cpu
2 x 8gb 2400mhz Kingston ram
Win10 Home to Pro, then to Win11 Pro
