Cyrillic bug in WordPress. What is the reason?

Question

PHP

Site - smart2b.ru
The template for internal portfolio pages provides attributes. These attributes are displayed on the pages and are searched for.

Everything works well until Cyrillic is used in the attributes. Then they are not displayed on the page and, accordingly, the search does not work.
The problem with Cyrillic is only in the attributes, everything else works as it should. What could be the reason?
PS Encoding of tables in the database

Answer 1

table encoding in database check where attributes are stored