Hi,
Hope you are doing well. Did you disable the Power Down functionality? This can be done in the app_preinclude.h (cPWR_UsePowerDownMode). With the Power Down mode enabled, if no key is pressed in an interval of 5 seconds, the sensor node disconnects and re-enters cPWR_DeepSleepMode
For more information about the Temperature Sensor and Collector, I would recommend the "Bluetooth Low Energy Demo Applications User Guide.pdf" (Path: SDK_doc.zip\docs\wireless\Bluetooth).
Hope this helps.
Best Regards,
Ricardo