I use the desktop app without any problems but the Android ZOHO mobile app could use some fine tuning or I am missing some functionality.
1. The app doesn't fetch mail unless you open it which means no message on the icon like the desktop app.. I use a Samsung Galaxy S9+. Before switching to the ZOHO app, I used the Samsung mail app. It could be set to fetch mail at different settings and new mail would register on the icon.
2. I have Categories (Distribution Lists) setup. However, the ZOHO mobile app does not appear to be able to access them which means I can't send mail using a distribution list.