Error encountered while creating a new Customer on MC and POS : customer group: Default

Error encountered while creating a new Customer on MC and POS : customer group: Default

Environment:

iVend 6.6 with SAP B1 9.2

Problem statement:

While trying to create a new customer on store MC or POS, it was throwing below error



The POS log file is capturing the below error.
<Category>ERROR</Category>
<Time>5:42:06 PM</Time>
<Message>Load failed. Criteria - NHibernate.Criterion.QueryOver`2[CXS.SubSystem.Customer.CustomerGroup,CXS.SubSystem.Customer.CustomerGroup]</Message>
<ExceptionInfo>

Symptoms: 

Not Applicable

Resolution/Work Around: 

This error appears when more than one customer groups are set to Default. After setting only one customer group as Default, the error is gone and can create a new customer now.

Recommendations/Suggestion: 

Not Applicable