Using the CSV/XLSX import feature, I am able to successfully import all data for building a customer invoice, including analytic distribution on the product line. However, using a similar file and field structure for importing credit note data, I'm able to import ALL BUT the analytic distribution. 

The pertinent fields that work on invoices but not on credit notes are: 

• invoice_line_ids/analytic_line_ids/account_id
• invoice_line_ids/analytic_line_ids/name
• invoice_line_ids/name

Notably, if I export a simple one-line credit note from Odoo, delete the exported record, and then attempt to import it using the XLSX file, the credit note will not contain a populated analytic distribution field. 

In the absence of other information, I can't help but wonder if this is a bug.