Categories Disappear – Front and Backend

We want to take advantage of each post having a description meta tag, so we have to use a third party plugin for this. I personally do not think it has to do with any plugin, but rather a permissions issue and wanted to publish this here to see if anyone knows the solution.

Basically, we install a fresh files and fresh database of 3.9.1 (or even recent previous version). We add some categories. We add some posts and associate those posts with the added categories. Everything works great.

Then I add Yoast SEO or FV Simplier SEO (again, I don’t think it matters) and then I go to add a new post and NO CATEGORIES SHOW. I then go to the front end (what the visitor would see) and the category widget on the right side is blank. There isn’t even the Uncategorized reflected. I can, however, still go to the category/uncategorized page and it still shows posts associated with the uncategorized category.

In other words, the categories exist (I even see them in the database) but the front end and back end interface doesn’t show categories. I also try to add new categories and they don’t show up anywhere (front visitor side, back admin side, etc only in the database).

Again, I think it has something to do with permissions as I recall a long time ago someone talking about /tmp/ directory not being writeable. Any suggestions of how to diagnose this?