Image Error While Adding Images in New Custom Post

I click on Portfolio, click on add new. Nothing shows up when I attempt to Insert Media. I can’t search anything, and when I try to upload something I get:

“item-09.png
An error occurred in the upload. Please try again later.”

I then click on Media in the dashboard and I see that the file that had an error is actually in the Media Library.

Why would it register in the Media library but not be able to be pulled in or even foud when I try to ‘Insert Media’ when I ‘Add New’ in Portfolio? The file size is 10kb and it says I have upwards of 2mb to upload at once.

This is my second time running through this course, and I had no problems the first time. Everything seems to be identical this time around in my code and process. Two things have changed:

1.) WP update from 4.5.2 to 4.5.3
2.) Windows 10 update

I should note that I switched themes and was able to successfully add images to the twentyfifteentheme. So it seems like it’s an error with my theme or dashboard setup within this theme. I can’t find the error. I’ve tried altering a few files with advice online with no luck thus far. Anyone have a similar experience or idea.

– I’ve successfully added images to other themes
– I’ve successfully added images to a post like this last month (in version 4.5.2)
– I believe that my code so far is good on pages like style.css, page.php, etc. I’m wondering if this is some mistake in my dashboard.
– I have only Advanced Custom Fields & Custom Post Type UI installed as plugins – they’re compatible with my version of WordPress
– I’m using Team Treehouse’s WordPress course

Every other minor change in the practice videos seems to be working, but I just cannot add upload an image that appears in the custom post type. Because the image is a required field I cannot post the post. Maybe I can change it to not being a requirement and seeing if I can post and then add an image later?

Edit: I’ve removed the requirement to add an image in my Custom Post. I have no successfully created a custom post that I can view, but I cannot see an image because I’m still unable to attach one. Now though, when I try to attach an image, there seems to be some hope in that the bar starts at 0% and fills up blue, and theeeeen I get the same error.