I upgraded my Wordpress from 3.8.1 to 3.9.1. I am using the magic-fields-2 plugin for custom data, I have created a custom post type and a custom template for displaying single posts of that type. Everything worked fine before the update. After updating, all posts of this type use index.php in my theme directory.
I have tried creating single-post.php and the posts still use index. I copied my template to a new file, added a template tag to that file, and selected that custom template for a post, that post was rendered using index.php.
I have googled for over an hour without any luck.
Any help or suggestions appreciated.
-- EDIT 1--
The theme is a custom theme of my own making. It is not very complicated, just some custom css and some custom templates. I created the theme in 3.6.x and it has not changed significantly since then.
The template that single posts were using prior to 3.9.1 was single-suites.php (suites is the custom post type). It is still there, but it is being ignored. I copied that file to single-post.php which is supposed to be the next choice in the template hierarchy, but that file is not being used either. I made yet another copy of the same template file, and added a template declaration to it. I edited 3 different posts and selected this template file as the custom template (it was in the template dropdown list), published them and viewed them. All 3 were still using index.php as their template. Finally, I took everything out of the custom template file except the template declaration and an h3 tag just to make sure there were no errors in the template that would cause a problem (my error log was clean, but I was just being cautious). It would still not use the theme.
-- Edit 2 --
I am using the plugin magic-fields-2. That is my only plugin. If I disable that plugin then my custom post type goes away and all the posts associated with that custom post type disappear. These are the posts I'm trying to display I appreciate the questions and hope I have provided enough information to define the problem.