I'm being prompted to enter an amount for Line 16 on the "Recovery Rebate Credit Worksheet", but when I enter the amount and click "Continue" nothing happens.

Try your entry following the steps here to see if you can simply add your stimulus payments without any errors.

In TurboTax Online or Desktop, to claim the Recovery Rebate credit please do the following:

1. Sign into your account and continue from where you left off
2. Click on Federal in the left-hand column, then on Federal Review on the top of the screen
3. On the next page titled Let's make sure you got the right stimulus amount, click on Continue
4. Follow the interview

TurboTax will determine whether you are entitled to any additional stimulus. Any stimulus amount remaining due to you will show as a credit on line 30 of your form 1040.

See the image below for assistance.

Be sure to track any payments received should they finalize any legislation and begin sending more payments in 2021