Accrued prepaid fees (FX rate at start) fixed amount

If the prepaid fee is paid in another currency then the Legal entity's accounting currency the system will calculate the accrued fees in original currency and book it with the month end rate. If you want to accrue the fixed paid amount in accounting currency the following rows need to be added in Accounting amount types. 

Open accounting rules and add accounts on the new rows set up. 

When accounting of unrealised in run the accrued fees will be booked to the same FX rate as the payment. 

Also see article 

Accrued prepaid fees (month end FX rate)