Cannot send agent on mission

[Queex]

A tier 5 purple mission, ‘Things to do when you’re dead’, cannot be started, despite more than one agent meeting the stat requirements and there being enough intel/supplies/assets in hand.

Is there an undocumented requirement? Am I missing something?

[Pilchenstein]

The success chance needs to be at least 33%, the “required” stats are usually wrong if a mission has more than one stat required.