I really don’t know on that part though it could be of two possibilities. One is they probably have privacy rule where they only show you what they created and no one else gets to. Or two they don’t want to show it at all either way those are the two theories I could think of as of now.

Its hard to say, as I know some people who commission plenty of art, then only post a tenth of the stuff, or there will be long stretches of time when they're online at all to post despite the commissions being finished and posted publically, and I've seen other artists only appear in their own galleries but not the commissioners.

I don't think its something commissioners intentionally do to artists, but is something that can happen if the individuals have busy lives away from the internet as well.

it's not you. a lot of artists don't post commissioned art for a number of reasons. some prefer to let the commissioner upload theirs first so they get more recognition, some don't upload commissions for a set time, some prefer to finish their queue before uploading, etc

i've only ever seen one instance where someone didn't upload art because they didn't like it/the person who commed it, and let's just say they didn't last long in the fandom after that

Which places are they refusing to post, your own channels or their own channels?

Their own channels.
I know that different artists do things differently. I also respect that not everyone wants to show every work they complete.
But if nothing is said to me, I feel cornered in my own mind.

I see. Well, it's hard to comment on the motivations of other artists, but one thing to keep in mind is that at the end of the day, every artist is their own brand. Perception matters, and what artists choose to share on their own channels matters. Whatever you upload to your own channel is essentially an advertisement for your own brand.

For example, there are a ton of SFW artists that dabble in NSFW stuff. While they might be comfortable with drawing NSFW for other people, they might not be comfortable with sharing it on their own channels because again, that's not their brand.

Personally speaking, I'm not into vore myself, but if someone asked me to do vore as a commission, I might be comfortable with drawing it for them on the condition that they share it on their own channels, but I might not be comfortable with it on my own channels. It's just not my bag. I want to be known as the slime guy, not the vore guy.

Some artists refuse to upload someone's commissions if they contain stuff they don't want to be involved or get recognition from, most of them are fetishes. They do this to avoid other people to ask for the same thing, they probably don't enjoy it or just want to keep their gallery clean. Happened to me with macro pics.

A lot of artists I deal with stagger posts so that they always have things released slowly.

Maybe they have Patreon or similar where people can pay to view other artworks, or in some other cases they have alt accounts and separate galleries for content that doesn't fit their usual niche.

I never post anything I commission, simply because I'm on a terrible internet connection with even worse upload and I'm not willing to put up with the headaches. Especially since Furaffinity really hates my connection for some reason.

When I accept commissions, I do let them post stuff on their galleries. They paid for it, so they can do whatever they want to do with it.

Also, I could ask them if I could upload them too, or if they want to keep things in private. Sometimes I don't ask at all and just put things uploaded~