Spies disappearing without notification? (Save file included)

Here's the situation, as the USSR I research a spy agency on day one and get to work on raising communist support in Iraq. I also get the illusive gentleman advisor and put a second spy on the same mission in Iraq. I usually employ this strategy without issue and have never seen this happen at any point with any other spies.

In January, 1937, for some reason, my spies, one after one, straight up disappeared. No event pop up. Just gone and an open slot waiting 30 days to pick a new person. I didn't even realize until February when I got the reminder popup to recruit a spy. I know I didn't have any open slots and sure enough, I had two empty ones.

In fact, I had managed to save my game in between the two spies disappearing, so I reloaded and saw it happen in real time. Kim Philby just up and vanishes. File: https://file.io/PaEYLYU4MjFu

Anyone have this happen before? The only mod I'm using is player led peace conferences.