I'm also having trouble getting the UARTPassThrough sketch -- the example in the STBLE library -- to work. I'm using the Arduino IDE (1.8.8) with a TinyDuino Basic Kit (Coin Cell), BLE TinyShield (ST) and accelerometer TinyShield.
In my case, it appears the sketch never escapes the setup() block. At 9600 baud the serial monitor spits O(10) garbage characters (e.g. BLE StacQ⸮) and then nothing else. At 115200 baud the serial monitor floods with repeated BLE Stack Initialized ... UART service added successfully. messages. In both instances the baud rate set in the sketch and in the serial monitor window match properly. Screenshots attached.
In neither case does the chip become discoverable to scanning devices. I'm new to this whole Arduino/TinyDuino scene, so guidance from you more experienced folks is very welcome! (I emailed info@tinycircuits late this afternoon, but I figured it wouldn't hurt to ask here too.)
Andrew