Posts on mobile are still going to /dev/null. I will just have to imagine all the brilliant posts people are making, which I’ll never know about because they don’t show up in searches.
Ok, so here’s what’s going on. If you’re on the web, you can search for posts by tag (entering a # in front of your search entry). You can also however look for a post you know has the tag you want and click on that tag. In the latter case you’ll be browsing the tag rather than searching it. These results are two different sets of posts!
If you’re on mobile, searching tagged posts or clicking on a tag will always give you one set of results, which is the search-a-tag mode of the web.
If you make a post on mobile and tag it, your post will be put in the browse-a-tag result set. So the one you can’t see on mobile…
To find a post that was made on mobile, you will have to go to the web, find another post with that tag, click the tag and scroll until you find it. If that post was however a photo set, it will (on the web) show up as a low res text post. So you need to like the post, go to your mobile app, browse your likes and when you find the post, you can click on the photos to see (download) them in full resolution.
Thanks for the update Tumblr.