I just got off the phone with Spot customer support and there was a server crash that caused the issues. The good thing to know is that any SOS activations go straight to law enforcement/ SAR and not through their servers - so emergency rescues would have been summoned if needed. It was only tracking and check-in/custom messages that were affected.
I asked if they could please post something publicly to let folks know about the issue since there are a lot of people 'home' watching folks out in the field and thinking there are issues when it was Spot's server crash that is causing messages to not get through.
