Classified ads won't post photos

I'm using the Classifieds plugin and it will allow ads to be posted, but they will not allow photos to be posted. When creating the ad, you can click the Add Media button and add them, and they show up in the editor, but when you actually publish the ad, they don't show up on the site.

You can also set a featured image, but it won't show up either. However, if you go back in and edit the listing, you can select the featured image and it will show up on the site, but it never works when creating a new ad. However, adding images to the ad itself (other than setting a featured image), doesn't work even when editing an existing ad. Again, they show up in the editor but will not show up on the site.

I contacted my host about this and they tried to troubleshoot it but said I'd need to contact you. They said to pass along this error that gets generated in the error log:

[Fri Feb 24 14:04:14.720977 2017] [:error] [pid 30151] [client] PHP Fatal error: Call to a member function switch_to_locale() on null in /nas/content/live/needgreater/wp-includes/l10n.php on line 1277