Can't Empty Spam on iOS Mobile

Hello,

My customer (using a different Zoho account from the one I'm using here fwiw) can't empty spam (or trash) on her iPhone 6s.

I can sign into her account on my desktop and everything works fine, so this is just a mobile Zoho Mail app issue on her end.

When she selects her spam folder and the list of spam email is displayed, she then touches the "empty spam" button, which seems to work fine. The folder is emptied as it should be.

However, when she returns to her folder list, the parenthetical number of spam emails is the same number as prior to that emptying, and going back into the spam folder reveals those spam emails are still there.

She contacted Zoho support, and they told her to sign out and back in, but that didn't work. She also tried turning the phone off and on without any improvement.

I studied her device to see if there are any relevant settings that might have been somehow changed, but I could find nothing (noting I'm an Android user, so unfamiliar with iOS fwiw).

My next step would be to reinstall the app.

Is there anything else that I should be looking for to address this issue?

Thank you for any help you provide.

- Scott