Vimeo featured images no longer working

I have followed the instructions on the Video Thumbnails Options page, going through each and every step.

1. I have saved the post multiple times.
2. I am not using a special field, I am pasting a Vimeo standard embed, and even have cut and pasted the video URL itself at the top of the post on a line followed by a CR so it can find it, nothing.
3. I have done the “Test Markup for Video section, no thumbnail is found
4. The Test Image for Downloading” option no longer exists, so I tried the “Test Video Providers, and Vimeo fails the iFrame Embed, returning a 404, the Flash Embed with a 404 and the Channel URL with a long string of characters.
5. I then tried the “Test Saving to Media Library” option, worked fine
6. Nothing particularly relevant in the support threads
7. Here is the embed I have been using, it’s the bog standard Vimeo embed:

<iframe src=”https://player.vimeo.com/video/358557481&#8243; width=”640″ height=”360″ frameborder=”0″ allow=”autoplay; fullscreen” allowfullscreen></iframe>

The URL of the page I am working with is nothing special, every video fails to get the featured image, so just putting the page in for the reference.

https://www.myascendedmasters.org/2019/healing-service-at-the-ashram-of-the-world-mother-1977-10-26-part-01/

Thanks,

RB