MSPM0G1506: Using BSL with non default UART

Tool/software:

Hi,

I managed to flash my application via UART BSL on the mspm0g3507 launchpad with default UART pins (Tx = PA 10, Rx = PA11).

But when I try to use my own board with non-default UART pins (Tx = PA 0, Rx = PA1) it fails. I changed wiring on one of my boards to default UART pins and it works.

Is the BSL only usable with default UART pins (Tx = PA 10, Rx = PA11)?

I understand I must use the default UART pins when I want to flash blank chips. But with an application running with configured non-default UART pins for BSL, it should work.

Thanks in advance 

Matthias