I've had some issues getting BLE to work in tandem with semihosting. If an error message is output while some BLE is in progress then it gets stuck. I discovered that I'm not alone, and one of the guys at Nordic actually says that it is better to use the hardware UART for debugging.
Today I have gone back to using the UART pins 8,9,10,11 which means I had to give up on a couple of LEDs. Notice that I have reworked the spreadsheet for TS06.2 to omit those two LEDs, so if you have not wired them up, then don't.
Of course it doesn't matter if you have already put LEDs on because I can just remove the jumpers, but I know adding LEDs is a pain, so I hope I caught you in time.