You don’t mention what version of HA you’re using or what browser, both of which would be helpful. I will say that if you are using Safari on recent versions of Mac OS, you need to update HA to at least 2023.4.0. There was a change in how Safari renders CSS that caused an issue with viewing YAML configs in the GUI that is fixed in HA 2023.4.0 and later.
Now I have installed HA 2023.4.2.
With Safari yaml config for add-ons does not work at all.
I cleared cache and refresh page and still it’s not working with Safari.
With Firefox yaml configs work ok.
There is still something wrong with SSH&Web Terminal add-on.
When I try to edit yaml config, HA displays both UI & yaml config.
Below is screen capture (Firefox) in yaml config mode of SSH&Web Terminal add-on.
SSH&Web Terminal log is ok.
Anyway all seems to work ok.