This could be due to a couple of reasons:
1. The Sales Invoice: Disbursement permission may not be allocated to your user account. Please check your user permissions to ensure this is enabled.

2. The automation setup for disbursements may not include the correct document types. To check this, navigate to the automation settings and confirm that the relevant document types are selected. If a document type hasn’t been included, it won’t appear in the disbursement selection.

Please note: if you add a document type into the automation settings now, it will only apply to new documents created from that point forward. It will not retroactively apply to existing documents. In such cases, you’ll need to recreate the original documents for them to be picked up correctly.