Project Costing - Batch description empty in the table PJC_EXP_GROUPS_ALL

In our company we created a custom project transaction source "Spreadsheet" and document "Accounting Journals" in order to book manual accruals on project level.

We want to use the "Batch Description" field in the "Create Costed or Accounted Transactions for Third-Party Applications" template, but when we fill in the field (see screenshot below) and upload the cost, the column DESCRIPTION of the table PJC_EXP_GROUPS_ALL is empty.

Do I need to enable something to have it filled in the column DESCRIPTION? Or am I looking at the wrong table?