I checked our system and I found no reported issues about updating employees' information. Although, I can narrow it down with an error message. If you've encountered one, please add it to your reply. That way, I can come up with a resolution to fix it or provide more details about it.
In the meantime, you'll want to do the steps below to help you update your employees' information.
This might be caused by a cache-related issue. When a storage is full or corrupted, QuickBooks Online has a tendency to show errors on webpages. You'll want to use an incognito or private window to rule this out:
Safari (new versions): Command + Shift + N
Google Chrome: CTRL + Shift + N
Mozilla Firefox: CTRL + Shift + P
In the private window, log in to QuickBooks Online as you normally would. Then, edit your employees' information. When you're able to do so, close out the private window and go back to the regular browser. Next, clear the cache to remove the corrupted data.
After clearing the cache, close all instances of your browser to apply the new cache settings. Alternatively, use another supported browser. Each browser has a different cache storage folder.