It could be your VG I guess. .I doubt it's bad, but when I was mixing with almost exclusively VG (I am PG sensitive) I would occasionally get a chalky juice, although that kind of leads me to believe it COULD have been a flavoring issue. To much ethyl maltol can definitely mute flavors. At the right percentage, it can add nice mouthfeel and body to juices, but I never use EM on its own, although I do use some EM "offenders' like merengue, marshmallow and cotton candy to round out mixes, but I use them in a pretty low percentage.
I will say, now that I am mixing with PEG400 (it's a PG variant) the flavors seem much cleaner, crisper, and not muted at all. I'm going to assume that PEG400 is a good flavor carrier, more like PG.
So I'd say check your EM flavors, maybe try less, and if you continue to get chalkiness perhaps look at raising your PG slightly.
I'm not 100% convinced of exactly what it is, I'm just kind of sharing my experience with that. I hope you get it sorted out.
Anna