When working with Project Invoice Proposals in Dynamics 365 Finance, the system currently allows an inconsistent and confusing user experience.

After creating an invoice proposal and selecting Add lines, it is possible to:

• Select another project contract that is linked to a different funding source, and
• Select project lines that do not belong to the funding source of the invoice proposal.

Although the system correctly does not add these selected lines to the invoice proposal after clicking OK, there is no validation, warning, or error message explaining why the action failed. This gives the impression that the system accepted the selection, while in reality it silently ignores it.

This behavior is misleading for users and can lead to confusion, repeated attempts, and unnecessary support escalations.

Expected Behavior

• The system should prevent selecting project contracts or lines that do not belong to the same funding source as the invoice proposal at selection time, or
• Display a clear validation message, such as:
• “The selected lines do not belong to the funding source of the invoice proposal and cannot be added.”

Business Impact

• Reduces user confusion and incorrect assumptions about system behavior
• Improves usability and transparency in Project Accounting processes
• Prevents unnecessary troubleshooting and support cases caused by silent system behavior