Steps to reproduce

1. Add custom classes and atributes - doc
2. Create an article
3. In Intro field, create a table
4. add to cell multiple line text
5. Try to add custom classes or atributes on row table

Result

the custom attributes and classes icon is grayed out and nothing happens

Expected result

Possibility to add custom classes and attributes

Note

If the cell contains text in one line or is empty, the option of adding Custom classes and attributes works correctly