Issue in lead conversion using Zoho CRM mobile

Issue in lead conversion using Zoho CRM mobile

I am facing a problem with my sales team who are using CRM mobile app where some device does not allow the lead conversion and other devices is working fine even with the same user account

The issue is when user choose to convert a lead to a potential and feed all the related mandatory fields and then submit the lead is removed from lead list and doesn't appear under potentials then after log out and log in again the lead re-appear as a lead while doing the same with same user account through anther device all is okay!!!

Need you advise in this regard ASAP