There is an issue when both UARTs are used at the same time at lease with TAG3 (with 20737).
I noticed that data in peripheral UART sometimes gets corrupted.
This never happens when running in HCI mode, but happens in APP mode (when HCI UART is used for debug).
I narrowed down the problem to the ble_traceX function.
The more ble_traceX are executed the more chances for a corruption on peripheral UART.
This happens only sometimes but it is easy to reproduce.
Any suggestions ?