There could be a few reasons why you don’t see your post. Here are some things you can check:
Make sure you’re sorting posts by new
By default, most communities sort their posts by hot, which prioritizes posts with the most upvotes. If you’ve just made a new post in a community with a lot of upvoted posts, you may not see your post unless you sort by new.
Double-check the community rules
Some communities have guidelines around how to format your post or what should or shouldn’t be included. If you accidentally missed something and broke one of the community’s rules, a moderator may have removed your post.
See if you have community karma
To prevent spammers, there’s a limit to how often redditors can post and comment in a community. If you’re brand new to Reddit and don’t have a lot of karma yet, you may be hitting this spam filter. If you’re brand new to a community that’s especially sensitive to spammers, you may also be hitting this filter.
If you think a spam filter removed your post, even earning a small amount of karma by commenting on another post within a community, can help you get past the filter.
If you think a moderator may have removed your post by accident or unfairly, send them a Modmail message.
If you have more questions that aren’t covered in these FAQs, check out r/help. Someone may have had the same question, or you can ask a new one and a Reddit administrator or one of your fellow redditors will help you out.