To be honest, I'm not sure if I'll like UEE as a solo artist.
She is beautiful, has a great voice and can dance but I don't think she's strong enough to go solo. Maybe that's why it's a good thing Pledis decided not to promote this song on Music shows.
EDIT: Come to think of it, about those tweets; Could it be that it is about UEE's solo song?
What if it has already been decided that Joo, JungAh and Bekah would form another sub unit. But the "debut" of this sub unit got pushed back because of UEE's solo song?

It's just a thought