Issue:
The Details button is greyed out when creating a Customer Filter in Omni Price and using a Range.
Cause:
The Details button is not available for Ranges that use text fields, such as Customer Name or User-Defined fields. It is only available for fields that have lookups.
In order to use the Details button to select specific records to include or exclude you would need to use a field for the Range that is a lookup, such as Customer ID, Salesperson ID, etc.