Unable to determine mime type of URL

In installed the plugin as I have had an issue with another plugin about mime and images.

[body] => {“errors”:[{“code”:”INVALID_DOCUMENT”,”keyPath”:[“root”,”metadata”,”thumbnailURL”],”message”:”Unable to determine mime type of URL [https://monarchhousing.org/wp-content/uploads/2016/06/rental_assistance.png]”}]}
[response] => Array

With your plugin how do I make sure the Mime is correct for each image.

I saved the settings from the plugin which I thought solved that but it seems to be unresolved.

https://www.ads-software.com/plugins/wp-add-mime-types/