Dynamics CRM 2016 Excel Import Issue

Hi All,

My client is using Dynamics CRM 2016 version On-Premises. While importing appointments in CRM using excel, we are getting unexpected results. Some of the appointments (customized entity) are getting updated from the excel sheet which gets imported successfully in CRM, but few fields remain as they were earlier. Please note there are no failures or error message while import. What could have been probable reason behind it?

Any pointers will be helpful.

Thanks in advance.