This is the first that I have heard about this. As others have said, it is a good and sensible decision for her to make -- I think.
On the other hand, I think that she could have had an integral role on the 2016-17 UConn team, mainly as a backup to Lou at the wing / small forward / third guard position. If her 3-point shot were working, she might have been able to earn 15-18 minutes per game, and not just in garbage time.
This leaves the 2016-17 roster without any real depth in 3-point shooters. If (as I assume) UConn has an initial starting lineup of Natalie / Napheesa / Lou / Gabby / Kia, then the only two genuine 3-point threats among those five are Lou and Kia. Off the bench, there would be Crystal -- and then who? Kyla? Molly? It's not a fatal problem, but it is an annoyance -- rather like the absence of a dominating big player (also a problem in the upcoming year).
What I observed consistently about Courtney Ekmark is that while her athletic ability (especially speed and quickness) was quite limited relative to her teammates, her head was always in the game and she hardly ever made a mental error when she was on the court -- and certainly never made the same one twice. She was never (well, hardly ever) out of position on defense. That meant that she had a role on the UConn team that was quite similar to Kelly Faris's role on the Connecticut Sun -- and resulted in the same limited minutes.
I think she will be missed on the practice floor and in the locker room for the guidance that she could have offered to the five new players. I think she will thrive as a Sun Devil.