You may need to need to whitelist the domain for our updated image uploader. The corporate filters or firewall filters may be blocking your ability to upload images. You may need to contact your tech department if you have one, to have this done.
Here is some context you could send to them
Our email newsletter service, Flashissue, has recently updated their image uploading feature to its latest API last weekend. Today, we were unable to upload images with their updated image uploader. This may be due to the update they made to the image uploader. Flashissue's support team has asked if we could make sure we have the following domain whitelisted so that we can access the image uploader inside the extension.
Here is the domain: