Missions randomly disappear from farm list

Amphistaff

I had this happen to me twice yesterday and consistently see this with some missions. When I click an item to see where I can farm it, sometimes a mission won't display there that I know drops it. Specifically I was looking at 1* Power Cells and wanted to farm it from The Toss on the 6 chron mission. This mission consistently disappears from the list and doesn't reappear until I restart the game.

Yesterday I restarted, was able to see the mission, and then a few minutes later I tried to farm it again and the mission was gone.