I would assume that Tachibana was the reason for the initial hiatus, since it doesn't make much sense that normal ongoing contract negotiations would cause Cover to suddenly tell them to stop streaming effective immediately, despite having schedules announced.
Here's my take: the Tachibana leak started the hiatus. The long-ass time for a resolution blindsided Magni and Vesper. Looking at what happened to Roa, japanese law is fucked up. With this being an international case, Magni and Vesper couldn't really afford to not stream for a long ass time so they decided to just fuck off and graduate and let Cover handle the case.
Remember, just my RRAT.