Form CEXCABMR.fmx in R12.1.3 does not populate Amount

There is a problem on this form when users are moving through the form via mouse and not using "tab" on the keyboard.

End user wants to create line from the bank statement, type Miscellaneous. Organization is populated automatically and user enters the Activity. Then next step is to click on the Method and select one from the list. When this is one, Amount is not populated. End user needs to enter it manually and they are not happy with the system behaviour.

Is this known issue? Because if I use "tab" or click on any other field it will populate the amount.