It was "encumbrance" as "burden": I wrote "the problem remains important", i.e. it is "massively" significant, and also a "massive burden"; "important" as in "w

It was "encumbrance" as "burden": I wrote "the problem remains important", i.e. it is "massively" significant, and also a "massive burden"; "important" as in "with priority" and as in "of uneasy volume". ("Important" contains an idea of "carrying something big".)