eNewsletter content editor working for "administrators" but not "editors"

The eNewsletter features seem to be working normally for my users with "Administrator" level privileges, but I'm having problems with "Editors," even though I activated all of the capabilities for them under eNewsletters > Settings > User Permissions.

Instead of the normal editor appearing under Email Content:
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My Editors just get whit HTML text on a white text box:
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The Editors can highlight and change that text, but it doesn't actually register as a change that shows up in the preview or allows them to save. I would like editors to be able to send newsletters without having to give them admin permissions, so anything you can do to help would be much appreciated!