Through pa20, look at IT2002 and IT2006 for employees whose Quotas get generated correctly, and note the PSA Groupings and ESG Groupings (for Attendances and for Quotas).
Through pa30, try creating an IT2002 and an IT2006 for employees whose Quotas do not get generated, and note the PSA Groupings and ESG Groupings (for Attendances and for Quotas). Note that you don't have to save the Infotype, you are just looking to confirm the groupings.
Next, look at your configuration to identify what is missing, using the documentation available in the Time Evaluation Wiki, or on help.sap.com.