Composer Feature - Blog content disappears
Permalink1. From the full sitemap I click on add a new page and select 'Blog Entry'.
2. I fill out the Standard Properties and click 'Add Page'. This drops me back into the full sitemap.
3. I click on the newly created blog entry page and select 'Edit in Composer'.
4. I fill out all the info and add blog content.
5. When I click 'Save', 'Preview' or 'Publish Changes' the Blog Content disappears but everything else (tags, description etc.) saves.
When I edit the blog entry from Edit Mode the content that I add saves just fine. Does anyone have any ideas about what may be the issue with the Composer Feature?
Thanks!

When I go to 'Page Types' I can see that my theme isn't listed as the Package for this page type (see screenshot). But when I go into 'Defaults' the page does apply the correct theme.
Within the Themes > Inspect area I checked that the theme does include a blog-entry.php file. Maybe it just hasn't been installed properly? How can I make sure this theme is correctly associated with this page type?
Am I wrong? Let me know please!
Rony