Welcome to the Community. Let me share some clarification about the Tags feature in QuickBooks Online.
The new Tags feature is always enabled. The option to turn it off in the Self-Employed version is unavailable.
Since it's no longer showing on your end, the browser's stored cache may be full. It can cause unusual behavior, such as being unable to include tags in the transactions.
I'd first suggest logging into your account using a private browser. It doesn't store data in the cache and is a great way to isolate browser-related issues.
Use these keyboard shortcuts depending on the browser you're using:
Google Chrome: press Ctrl + Shift + N
Mozilla Firefox: press Ctrl + Shift + P
Microsoft Edge: press Ctrl + Shift + P
Safari: press Command + Shift +N
If the option is available, let's switch back to the regular browser and clear its cache & historical data. This helps to restore the default setup of the browser.
If private browsing doesn't work, use other supported web engine to get the best and most secure experience with the program.
You're always welcome to post any questions you have in this space related to the QuickBooks features. I'll be happy to help you some more. Have a good day.