When attempting to request exemption from NetSuite interface I receive 'Exemption Certificate workflow request cannot be initiated because communication mode is missing.'
In NetSuite, before requesting for exemption certificate, user needs to select respective Address row for which the request to be initiated and on the same row Communication mode to be selected. Make sure whatever communication mode is selected, respective details must be available on Customer record. (e.g. if 'Email' is selected as communication mode then respective email address must be available on the address row or under 'Email,Phone,Address' section).
See Exempt Customers from Tax (sections i.e. 'Add a customer record to CertCapture from NetSuite' and 'Request an exemption certificate')
If emailing, the cover letter for the request that is sent comes from the template STANDARD_REQUEST (located in CertCapture under Requests > Templates and Cover Letters). If this template is missing, you will receive the above error message.