The idea is related to fix this strange D365FO behaviour when you post fixed assets acquisitions and you have linked more than one book to this fixed asset on different posting layer. More concretely, if you have selected 'do not allow manual entry' to the acquisition fixed asset account and, besides, you are working with 100 non deductible % tax. Then you will receive a worried warning message when you try to post the acquisition using 'fixed asset', as account type on ledger line, this message inform you are not allowed to use manual entries. It is a true contradiction.

Regards