Receiving missing data in UART1


My Open AT application reads some data from a device through UART1. My module can not receive the last 112 bytes of data sent by the device. What is more, when module sends second request to the device inorder to get the data again, the missing data is also received in uart1 data handler function.

I suspect that some internal buffer of uart1 keeps the missing data. So i executed adl_fcmGetStatus function for uart1 but that function returned ADL_FCM_RET_BUFFER_EMPTY for both ADL_FCM_WAY_FROM_EMBEDDED and ADL_FCM_WAY_TO_EMBEDDED parameters.

if there are no internal buffers keep my last part of data, then where do my data go?
The problem occurs only Fastract Xtend FW: R7.43. Supreme with FW:R71.b is just fine!

Is there any function that flushes the internal Rx buffer?

Or is there any function that triggers uart_data_handler callback function with all data in Rx internal buffer?
I am almost sure that the module keeps some data in its internal buffer and does not send to data handler function of uart.

If there is no solution with FCM service, then can i use any other service that handles uart1 operations?