Fast User Switching cannot be activated

After updating to 13.2.1 and the problem persists give this a try: boot into Safe Mode according to How to use safe mode on your Mac and test to see if the problem persists. Reboot normally and test again.

NOTE 1: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

NOTE 2: if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode. This makes it act as a wired keyboard as will insure a successful boot into Safe Mode.

Is user profile true and accurate iMac 27″, macOS 13.1 ?

Predicated on above as being accurate.

The current version of Ventura has moved on since that time.

Current version has now reached version 13.2.1

There have been several bug and security fixes that maybe be related to the Faster User Switching issue

Links below related to Updating and Security update 13.2.1

Keep your Mac up to date - Apple Support (CA)

About the security content of macOS Ventura 13.2.1 - Apple Support

Welcome

To offer possible answers to above question regarding did not notify of the update

There are factors:

1 - Like poor Wifi connection

2 - Slow wifi connection

3 - Too many other people downloading at the same time and Apple Severs are overloaded

4 - Software on the computer interfering with the download process including AntiVirus Software

Notation: Disabling the AV Software may or may not solve the issue. Removal of the AV Software may increase the chances of the download to perform as expected.

5 - Running behind a VPN which may increase Packet losses or corruption of the download 

6 - If via wifi too many Other devices using the wifi at the same time reducing the Bandwidth to your computer. 

7 - Best Results are via Ethernet Cable to Router

I am having the same issue. Since updating from Ventura 13.2 to 13.2.1 a couple of days ago, Fast User Switching keeps switching itself off! I go into System Settings and switch it on with Show in menu bar - icon but after a while (usually after the Mac has gone to sleep) it sets itself back to Show in menu bar - Don't show. Very frustrating.

(2020 iMac 27" Core i7, macOS Ventura 13.2.1).

In the last few hours Fast User Switching from the menu bar has become unavailable. Go to System Settings - Control Centre - Fast User Switching, it now shows as "Don't show" and won't allow me to set any other value, it just immediately changes back to "Don't show". This is new behaviour since Ventura 13.2.1.