The REAL Reason Your Posts Don't Show Up In Tags
[What Tumblr Doesn't Want You To Know]
You might think you know all about Tumblr's post and tag limits, but here's what they don't want you to know and why Tumblr will never ever have any commercial business value to Yahoo.
Tumblr intentionally prevents more than 3 posts from the same blog to the same tag within 24 hours.
Your post can have ONE tag but when you tag a 4th post with the same tag in 24 hours, the 1st will 'disappear'. Delete / mark private a post, the 1st 'magically' reappears under the tag.
Try it... Create 3 posts tagged with ONLY a single tag. They'll all be under the tag. Create a 4th post with the same tag, you'll see the 1st post will missing!! Delete / mark private or remove the tag from one of the other posts that does display & your first post 'reappears'.
If you go back through your post history and see huge chunks of posts missing, you'll notice if you delete, mark private or remove the tag from some of the posts -- posts from that same 24 hour time period which previous didn't appear -- now appear!!!
Tumblr doesn't document this great 'feature' which essentially eliminates any type of [non-spam] business type usage of Tumblr that wants to promote itself by contributing to any one topic.
If you contact Tumblr about this issue they'll play stupid and send you emails about how only the first five tags are read [even if you clearly told them that its the ONLY tag which appears in the post] and go back and forth with you for WEEKS playing like their STUPID when you ask them WHY you can't create more than 3 posts under the same tag from the same blog within a certain time period or ask them what that time period is. [Or maybe their support people are just stupid -- as I was able to troubleshoot THEIR service and discover this]
Workaround
Create MORE BLOGS !!!
The limitation isn't per account, it's per blog so if you own multiple blogs, you can create 3 posts from each blog for the same tag within the same 24 hour period.
Using tags to get followers? Just add a note at the bottom of the posts from your secondary [& tertiary blogs] with a link or follow button for your main blog.
Don't forget to include a little explanation about Tumblr's undocumented post per tag per blog limitation. Apparently Tumblr's infrastructure can handle a single account having dozen's of blogs, but their tagging / tracking code was written so poorly, they had to [secretly] intentionally introduce a 3 post per tag limit for each blog.
As a software engineer, I can tell you that had they properly written and implemented code for tagging and tracking, it would be a lot easier to manage and maintain the tags and tag tracking by allowing MORE posts per blog [especially when they only allow 200 posts per tag total ANYWAY] rather than overloading their entire infrastructure by having users create additional and unnecessary blogs simply to get around the limitation anyway.