We've received multiple reports about the Accountant tab not showing in the Manage Users page, mmph.
Our product engineers are working their best to have this issue resolved. As a workaround, kindly log in using this website and see if you're able to add an accountant.
If the same thing happens, I'd suggest contacting our Customer Care team so you'll be included as one of the affected users. Thus, we can send you an update via email.
Here's how to contact them:
The Community is always around to help if you need anything else.