This applies to the base v3.2 game (no Crusade or Intrigue).

The various planetary Projects (Military Subsidies, et al) are marked with the <Unavailable> tag and don't show up in the planetary Build queue, but they do still show in the Tech Tree. Their absence means that when a planet's tiles are fully developed, the game is thrown into an endless "Idle Colony" loop.

Disabling the <Unavailable> tag (found in PlanetaryProjectDefs.xml) restores access to the (viable) Projects, thereby avoiding the "Idle Colony" loop.

If the Projects were meant to be replaced by a new feature, that feature isn't showing up; which might be the real bug.