I have encountered a strange issue on a site I am working on that has been active for a few years. (Drupal core 7.54) If I edit or add a new Taxonomy term, then the Taxonomy term will no longer show up on the Taxonomy term overview page (i.e. /admin/structure/taxonomy/[vocabulary]. The term will also not show up as an option to select on a node with a corresponding term reference field.
However, if I make a view and set it to display all terms of a certain vocabulary, all the terms will show up normally. If I use Taxonomy manager module, I can successfully create the terms by adding new terms in bulk, but as soon as I edit their fields, they will disappear. I have searched far and wide, but have not encountered an similar problem and solution. Can anyone help? Thank you.