Chloe is no longer at ALDC.  She left that studio about a year ago.  Since she is only there for filming, I can see why she would not be a part of the recital.  Chloe has improved a lot since leaving Abby and Abby can't stand that.  Abby is such a bitch.

She left the studio, but I doubt she has actively been training at another studio, at least until very very recently.  According to Christi, between school, homework, traveling for comps, filming, "touring" and all the meet and greets they do,  Chloe has basically no free time.  I don't see when she'd be taking classes regularly anywhere else.  

I love Chloe but haven't seen much improvement in her dancing for a while now.  It's kind of impossible to say though because we basically don't get to see Chloe dance on this show, and when we do, its always the same uninspired choreography. To me she seems a little stiff, but it cold just be Abby's choreo. Same for Mckenzie and Nia.  I see Mackenzie improve in the sense that she's getting older and her dances are less cutesy, but I don't see her becoming a "better dancer".  The only ones I personally can detect improvement in are Maddie and Kendall, but that's just me.  

I think Christi is right in her hatred of Abby, but she is also really annoying and I think she encourages a lot of unneeded melodrama when it comes to Chloe.  Instead of offering her young sensitive daughter a little wisdom and perspective in the vein of 'its not the end of the world, abby's just a bitch, nationals won't make or break your life, etc.' she kind of milks the whole thing and enables the drama.