Today we switched to Shopify and I realized that the titles and descriptions I set do not appear as meta. Meta titles and descriptions appear as missing. This is a big problem. Please help me!
Edit: I solved. Yoast SEO blocked all my meta markup. Even if I uninstalled Yoast, these blocks continued. When I deleted the Yoast codes in the meta related places in the theme.liquid file, it was fixed
I can imagine how troublesome this might have been, and I am glad the issue is now resolved, but I'd like to offer some clarifications on the matter that may be useful in the future (if you use Yoast SEO again) or anyone else reading along.
Yoast SEO, when installed, will override (but not overwrite) the meta details you have set, based on the default Content settings of the app, as it integrates with your theme. However, most of the default options in the app pick up the already set details you have in Shopify's default editor.
In case those meta details are not picked up after the integration with the theme, it could be due to the way the header section is formed (for example an early close of the header will not allow the app to pick the metadata set) or theme code structure.
Still, the theme integration can be reversed (there is a menu where you can remove the integration and return to the state you were before) and rectify this, or you can completely and properly uninstall the app. If you noticed leftover code from our app after the uninstallation, that means the app was uninstalled without following the right process (which requires first deactivation of the app to remove theme modifications and then deletion of the app), or if there was an interruption during the deactivation/uninstallation, or if another (usually SEO-related) app interfered with the process (if you have/had one installed simultaneously with our app).
There are 3 ways to remove leftover code in such cases, and the easiest one is simply to reinstall the app and, instead of starting a subscription, select the option "remove theme modifications". This will remove any leftover code.
Manual removal, as you have done, is also an option, but that is a more time-consuming process that can be avoided with the aforementioned way (or through Yoast support when requested).
In all cases, I am glad you have resolved this but do feel free to contact Yoast SEO support if you require any assistance related to the app in the future. I am sure they will be able to help with minimal involvement and actions from your side.