Sleep + WDT

Has anyone succeeded in getting SAMD Sleep to wake up from a WDT interrupt? I've had success with the following scenarios:

1) Just sleeping 2) Just WDT-resetting 3) Sleep + RTC wakeup

But I cannot get

4) Sleep + WDT wakeup

When I try, device seems to immediately wake right back up again. If anyone has been able to get Sleep + WDT to work together, could you please show your code? Thank you! (I've posted this question here also)

For the record, I'm using Adafruit M0 Feather and Sparkfun SAMD mini - technically not Arduino Zero, but should be close enough.