Timesheet standard link field for Sales Invoice not showing

Dear ERPNext Community,

on the Timesheet there are two standard link fields for Salary Slip and Sales Invoice.

When creating a Salary Slip from the Timesheet the Document Name (Sal Slip/HR-EMP…) is populated in the Salary Slip link field and the Salary slip can be opened and filtered using that field.

Unfortunately the Sales Invoice field does not get populated and it not showing at all when the timesheet is billed.

When opening >Menu > Links - the Sales Invoice is there but not getting populated in Sales Invoice Link field.

How do we get the Sales Invoice link field in Timesheet linked with the right Sales Invoice, or is there a alternative approach you would suggest?

Working on Release v12.14.0