I've got some troubleshooting solutions for you to access the Workers Compensation Tax Setup, Darina. 

I've checked our records and there's no reported case about this one. There are times when a browser's cache data becomes full of frequently accessed websites or damaged. When this happens, it causes odd behavior when accessing the Workers Compensation Tax Setup option. To resolve this one, let's try signing in to your account using a private or incognito window. This mode doesn't use the existing cache data and helps us confirm browser-related issues. Here's how:

• For Google Chrome browser: Ctrl + Shift + N
• For Mozilla Firefox browser: Ctrl + Shift + P
• For Safari browser: Command + Option + P

Then, edit the list of codes and rates in your payroll settings again. Let me guide you on how to do it.

1. Go to the Gear icon.
2. Select Payroll settings.
3. Choose the Tax Setup tab
4. Select the state for Workers Compensation Tax Setup.
5. Click the Add Class and Subclass link.
6. In the Risk Classification Class and Subclasses then, enter the rate in the fields.
7. Hit OK once done.

See Assign a Workers' Comp Class to an employee article for more details about this one. If it works, go back to your regular browser and clear the cache to delete those temporarily stored files and browsing history. The overtime collection of data can create corruption, however, removing this should fix the issue. You can also use other supported, up-to-date browsers to roll out the possibility of a browser-related issue.

If the same thing happens, I'd suggest contacting our Customer Support Team to add you to the list of affected users. They'll pull up your account in a secure environment and send you an email notification once there's an update on this issue. Here's how:

1. Go to the Help menu at the upper right.
2. Select Contact Us.
3. Enter your concern.
4. Click Let’s talk.
5. Choose Get a callback. 
6. Type in your contact info.
7. Select Confirm my call.

I'll be right here to continue helping if you have any other concerns or questions about QuickBooks Online. Assistance is just a post away. Take care always.