I encountered this in the Dread Lords campaign. The issue is not actually a bug, once you make sense of it. The Dread lords never build farms on their planets, just industrial sectors. Sometimes, the initial colony doesn't even exist (or has been destroyed). It doesn't seem to bother the dread lords much, but then - they ARE the dread lords you know!
When you conquer one of those planets, however, your troops arrive on a planet with *0* food production. As a result, unless you rushbuy a farm on the planet, all your troops die.
Since you cannot launch a troop transport with 0 people on it, you can't launch the transport!
The solution is to rushbuy a farm on there; the pop will stay at 0, but you can then land a colony ship or troop transport and "relocate" some people to that planet.
What would help is if planets had an indicator next to the planet name (like the bars in CIV - yes, I'm a hard-core CIV player!) that showed population growth or loss etc... Also, in the planetary management screen, it would be mighty useful to not just see food production, but also the surplus, and whether the pop is growing or not, and by how much last turn.
Hope this helps!
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