If operating in callback mode, requesting only 1 byte, and this byte is received with frame error, the user callback is lost by the driver. This means that the UART quietly stop operations without the user knowing an error occurred. Following the execution path, It seems the code depends on UARTCC26X0_readCancel() to issue the callback but if readSize is decremented to zero during an RX error inside readTaskCallback(), UARTCC26X0_readCancel() will return early as there is "nothing to process". This means that the callback is never getting invoked and the driver simply stops as readSize will always decrements to zero in case we attempt to read only a single byte and this happens to be received with an error.