D&D 5E Cube of Force Conundrum

[CM]

Glad to see we aren't the only ones with varied opinions on the subject. Probably going with the LOS blocking interpretation.

 

[epithet]

An effect that does not require concentration can be carried across because it is affixed to the target of the spell. A spell that requires concentration cannot, unless the caster and the target cross the barrier at the same time (or the caster is the target.) A spell or spell effect cannot be maintained on a target on the other side of the boundary.

An easy way to think of it is that the boundary is, for the purpose of spell effects only, a vast distance and another plane of existence.