artists_beware | Advice Needed - Artist Neglecting Commissions?

About 8 months ago I commissioned an artist for a fullbody wing-it colored sketch and I still haven't received any kind of WIP, contact from the artist, or the finished piece and I'm not sure what the next step should be. At first I let a few months pass by without thinking much of it, then a while after that I began to get curious and made contact with the artist. They assured me that they'd simply fallen behind on their queue and that they planned to have their remaining pending commissions finished by the end of the week. A few more months passed after that and I tried to make contact with the artist again, but this time I didn't receive a response. The note was read but ignored. A few more weeks passed by and I sent another note, it too was ignored and now I'm not sure what I should do. Should I try to send them another note? Try to file a charge-back? I don't want to be a jerk, but I've been waiting for a long while now with no update and the lack of responses from the artist really has me worried. What bothers me most is that they're a fairly active poster. While I've been waiting they've posted multiple personal art pieces, held freebie streams, made gift art for friends and have created over half a dozen personal character designs. Normally I'd be totally fine with an artist working on personal projects between work. There's nothing wrong with drawing for yourself, but when your personal projects seem to be getting in the way of owed work it creates a bit of a problem in my opinion. Am I just being impatient? I don't want to be one of those commissioners who's constantly hounding an artist for the finished product.