Microsoft has determined they're unwilling (at this time) to resolve a known issue Sub-ledger reconciliation issue.

If Project is included in the ledger dimension account string, the use of accounting distributions allows multiple projects to be used, when releasing the Purchase requisition into a purchase order, there is a clear mismatch in the ledger and sub-ledger. The ledger account string only reflects the one project that was listed in the line details, leaving references to the other project dimension in the ledger account string.

The results of this will incur a mismatch between ledger and sub-ledger on the resulting vendor invoice if not caught by a user.