Content is not displayed in the MODX content editor - what to do?

Question

MySQL

The content on the site is displayed normally.
In the admin panel, some resources have an empty editor. If you save such a page, the content will disappear.
If you re-add content to the problematic page, everything works well (with subsequent edits in the admin panel, the content is visible).
As I understand it, the problem is either in the database (modx receives information that it cannot process), or in modx (I did not develop the project, it is not known what they could do with the kernel).
The encoding in the database is incorrect, there are problems with the Cyrillic alphabet. I tried to change cp-1251 to utf-8, it doesn't work.
SQL query to change encoding returns "This selection does not contain a unique column...."
I tried to change manually some of the tables and fields for the experiment. Some fields don't change encoding - "#1283 - Column 'description' cannot be part of FULLTEXT index".
What to do? Has anyone had this problem, how much would it cost to fix?

Answer 1

It was the unidentified characters. Perhaps they appeared due to incorrect encoding.
That is, those pages in which unidentified characters were present were not displayed in the admin panel, even the recoding did not understand them.
I had to recode the base dump, clean up the characters regularly.

Answer 2

Yes, the database must be in UTF-8. And also look at the editor itself.
Send me an email in my profile.