Canonical link error

Why does my post keep getting deleted?????

Hello. I have a problem with the Seo Yoast plugin. If the plugin is deactivated, the error does not occur. Seo Yoast sets an incorrect canonical link on the Avada portfolio page. Since it is the main portfolio page, I cannot edit it like normal pages. It sets a canonical link with a capital letter. A lowercase letter would be correct: /urlaub and not /Urlaub. How can I correct the canonical link? Thank you very much.