[Air node to Death Shard]

How the bug was found: 

I built an air node on top of an air shard. Several turns later, I attempted to cast the spell that changes the node to a death shard. The turn that I cast the spell, the node completely disappeared from the strategic map. Next turn, an unbuilt death shard appeared. The "build" icon and button appeared next to the shard when I selected it. Pressing the "build" button did not build the shard.

Additional details: The shard was under the zone of control of an outpost. 

[Cannot select treaties with opponent factions]

How the bug was found:

I attempted to make a trade treaty with Magnus(?) but I was unable to select the option in the diplomatic screen. I am unsure how to replicate this bug and it appears to be random in nature (I was eventually able to select the treaty several turns later).