With all the other plugins disabled, can you try saving your current post as a Draft.
And create a new post using the WP editor and publish that. Then let me know.
Ok – can you re-enable the other plugins and make sure the second test post is still working correctly.
If so – you may need to copy your content from the ‘broken excerpt’ post over to a new post. If that works then its just a database glitch. If it doesn’t then Elementor is doing something funny to the post excerpt.