[Resolved] Unable to add Alt tags to images

I am starting to edit https://easternhillsrenovations.ca/flooring/ for SEO.

Rank Math tells me to
“Add an image with your Focus Keyword as alt text.”

I have added alt tags to my images in the media library, but they are not showing up in the coding, and if I add the alt tag manually in the code editor, as soon as I update, it disappears.

Example:

If I add the alt tag of “flooring” in the Code Editor

<!-- wp:generateblocks/container {"uniqueId":"ba4ae159","innerContainer":"full","minHeight":400,"paddingTop":"0","paddingRight":"0","paddingBottom":"0","paddingLeft":"0","verticalAlignment":"flex-start","isDynamic":true,"blockVersion":2} -->
<!-- wp:cover {"url":"https://easternhillsrenovations.ca/gay-content/uploads/flooring-1400x400-1.jpg","id":1705,"contentPosition":"center center","align":"full","className":"has-parallax"} -->
<div class="wp-block-cover alignfull has-background-dim has-parallax"><img class="wp-block-cover__image-background wp-image-1705" alt="flooring" src="https://easternhillsrenovations.ca/gay-content/uploads/flooring-1400x400-1.jpg" data-object-fit="cover"/><div class="wp-block-cover__inner-container"><!-- wp:paragraph -->
<p></p>
<!-- /wp:paragraph -->

As soon as I update, the word “flooring” disappears.

Can you tell me how to deal with this please. I have requested support from Rank Math and they suggest I ask the theme author.

Many thanks!