tl;dr Firmware 1.3.1.10 removed due to unexplained "technical issues". Expect firmware 1.3 to be restored in the next 3 to 4 weeks (hopefully with an explanation).
From Cisco technical support:
"Based on your request I got the response from the esca...
Cisco rep got back to me yesterday. From his response, the case has been escalated up to the next tier. I suppose eventually the case will make it to someone who knows what is going on. Another 48 hour hold.
Response I received yesterday:
"As per nex...
I was able to start a case last week with Cisco Technical Support. They're expected to have more information today, but we'll see.
The heat is on to revert to 1.2.1.14.