For anyone who also has this (or a similar) problem:
Everything went awry when changed the pot-mode to Relative in the Global menu. On Relative, the Master Volume will go up to 100% (I was wrong in about the 50%) in my previous post. However, it won't go back down.
Setting the Pot Mode to Jump fixed the issue. Hope it helps however else has this issue!
(By the way, is there a way I can edit the subject of this topic? Putting a "solved" in the subject line would be nice
)