Undisclosed (No Subject), Email not showing & opening.

Undisclosed (No Subject), Email not showing & opening.

Hello There,

In my latest iPhone 12 device, I have set up the Zoho mail app yesterday which is not working properly, The same account is working good in Browser and iPhone 6(my older device).

since yesterday, mail notification is coming but when I click on it to open it shows Undisclosed and back to the main screen. also when I have written an email from Zoho mail app using iPhone 12 device as you can see in the video it's showing as a subject and email text but again while opening redirects back to the listing screen. 

I have already emailed you about this problem, Please check and fix this problem ASAP.

Device: iPhone 12
Version: iOS 14

Thanks.