Can no longer post in non-visual rich editor mode

This is how I used to post youtube embeds. In order to get youtubes to embed, I would need to uncheck the “users should use the visual rich editor by default” option in “options/writing”, and then simply post the youtube embed info in the post body.

This no longer works. In fact, I can’t even enter the non-rich editor mode, which I find very strange.

Thanks for any comments.

my blog:

https://www.wilderness-sportsman.com/wsblog/

Strangely, my past youtube embeds work – but if I edit them and save, they will no longer work due to the inability for wordpress to use the non-visual rich editor.