Note: While teraport systems must necessarily compensate for vector differences between source and destination frameworks, the mechanism is not perfect. Additionally, the teraport cage, a tool for masking and protecting the space-time disruptions a teraport induces, introduces significant computational and power-drain overhead. Add to that the fact that the beach-head teraport cage is open on two sides, and the imperfections in the vector-alignment mechanism become difficult to smooth out.
Now drop a beach-head cage down a hole in which teraports are disrupted and in which the gravitational field is changing in intensity, and you have a perfect storm of circumstances in which the vector compensation system shuts itself off lest it overheat and prevent teraporting from happening in the first place.
Fortunately, the sorts of circumstances in which troops will be launching themselves through beach-head cages for extraction are also the sorts of circumstances where their destination is equipped with systems for throwing a gravitic bubble around things that are moving faster than a high-velocity speeding bullet.