Softdevice assertion failed on new hardware

I have a simple central device where a gpio triggers the device to scan and connect to a peripheral.  This is running ok on the PCA10040, and also on a separate hardware platform that I had laying around that contains a BMD300 module with an nrf52832.  However, the new hardware board came in containing an nrf52832.  The code there will initialize and run, but on triggering a scan with sd_ble_gap_scan_start, it will immediately fail with:

    <error> app: SOFTDEVICE: ASSERTION FAILED: 0x00012A42

Where 0x12a42 is the PC which I added to the message.  All hardware platforms use the same code and sdk_config.h, the only thing I changed was the gpio pin #, polarity, and pullup.  There are no peripherals used, only connections are a gpio at pin 22 and AIN0 for measuring battery.  What could change hardware-wise that could cause the softdevice assertion?