Employees who are not assigned to a 1094 subgroup are skipped when 1095-C forms are generated. BerniePortal does not create a 1095-C for them and does not show an error for the missing assignment.
Before you generate forms, use the Employees filter option 1094 - Not assigned to find anyone still unassigned, then assign them to the correct subgroup. For the full check and organize steps, see: