The soc_evt_handler() function in nrf_drv_clock.c need to set m_clock_cb.hfclk_on = true.
When the softdevice is enabled and multiple modules request the HFCLK using nrf_drv_clock_hfclk_request() only the event handler of the first module is ever called (since hfclk_on is never set).
The issue is already fixed in SDKv15, but can be added to at least to v14, v13 and v12.