I am using NRF52 SDK14.0 and SoftDevice S132 v5.0.0. Application freezes somewhere in SoftDevice if sd_softdevice_enable() is called after nrf_drv_clock_lfclk_request() was called before. If using a debugger, you can pause while frozen and if you hit run again, the application continues flawlessly. It seems it is stuck in some strange loop inside SoftDevice. If you are not using nrf_drv_clock_lfclk_request() before starting SoftDevice, everything works just fine.