Prepayment COA "Bank Payment to Supplier" and Allocation Supplier

We have question regarding prepayment to Supplier,

we want to submit this with COA Account "Prepayment Account" and not directly submit to "Account Payable"
transaction details:

Bank Account Payment Entry
1. Pay To Supplier
2. with 11161010 "Prepayment Account"
3. Submit value 10,000,000

Purchase Order
1. Create PO with Supplier A
2. Items with total value 5,000,000
3. Receive items
4. Supplier Invoice

Allocate Supplier Payments or Credit Notes
1. Allocate $500
2. Shown total Left to allocate is correct 5,000,000
* checking with Supplier Balance shown also correct 5,000,000
* checking with GL Inquiry show that

Bank Payment # 1 1 05/15/2019
1501 Uang Muka admin (D) 10,000,000.00
1110 Bank IDR admin (K) 10,000,000.00
Total (D) (K) 10,000,000.00 10,000,000.00

Purchase Order Delivery # 11 05/15/2019
1420 Persediaan - Barang Jadi admin - 67099610 (D) 5,000,000.00
1416 Persediaan - Barang Diterima admin (K) 5,000,000.00
Total (D) (K) 5,000,000.00 5,000,000.00

Supplier Invoice # 1 1 05/15/2019 Supplier 1
2100 Utang Usaha/AP admin (D) 5,000,000.00
1416 Persediaan - Barang Diterima admin (K) 5,000,000.00
Total (D) (K) 5,000,000.00 5,000,000.00

Why is allocation to supplier using Account Payable instead using COA that used when Bank Payment to Supplier?
and how to resolve this? do we need manual journal to correct this?

need advice