Let me first say I'm sorry if you felt you're being ignored. We want to help. We only had a confusion here.
I think the confusion started with me when you said this in your previous reply:
Notice you said, "any post" not live post like you said later.
In my previous reply to you, I actually tested a post. But yes, I tested a test post because I don't want even a very small chance of accidentally ruining your live posts.
I tested again using the live post and I experience the issue you encountered (see first recording in Secure Note).
I suspected the contents in your live post (I tested this live post) so I removed elements with non-english characters and saved it as a new template then imported it to the test post afterwards and it works (see second recording Secure Note).
With that discovery, the issue is with the characters. This might not be allowed depending on the database setup or other factors in your server configuration. I can say that because I tested your template in my local dev site and it works (see image in Secure Note).