Hello there, @carol33.
Entering an employees' addresses in QuickBooks Online will go through once it is correct and valid. To determine the reason behind this issue, let's go ahead and perform some steps.
Checking out the employees' address on the USPS site is a good start to identify if its correct and accurate.
You may also see this link about the accepted code and addresses' format in QuickBooks Online: USPS standardized format.
Once verified and the issue persists, I'd recommend accessing your account using a private window. At times, the stored data can cause some odd errors and simply needs to be cleared from the browser.
If it works fine, you may get back to your regular browser and start deleting its cache.
However, if doing this doesn't make a difference, I'd suggest getting in touch with our Customer Care Team so they can check this matter for you and can open an investigation if necessary.
I want to ensure that this is taken care of for you, so please let me know how it goes by posting a reply. Take care!