Problem editing "some" images in posts

We are having a problem editing some images in posts.

Today is the first time we have noticed this problem and no changes have been made to our servers, php or layout of backdrop.

While editing some posts, we discovered on one published post was listed under the "content" on the backend, as a "page" instead of a post taxonomy TAG. However when trying to edit it, the layout was exactly the same as it would be for a post instead of a page, including listing the correct TAG.

Since we could not find out WHY it was displayed on the "content" list as a page instead of a post, we deleted it and reinstalled it.

Now, it appeared is listed under "content" as a post, however when we try to add multiple images, to the article, we are getting a strange reaction.

When we upload an image, it looks fine. However if we try to add a caption, and save the post, the image disappears. The other thing we have noticed is that if we try to add alternative text, we end up with extra code and an error stating we have entered too many characters. Here is an example of some "alternative text" that has shown up "without us posting ANYTHING in the alternative text box.

Eva_Hamlet_small1b_ 2004.jpg (9 K<img style='width:20px;height:20px;' src='https://uslegacies.org/images/smiley/cool.svg' alt='Cool' style='vertical-align:middle;' />

We realize this is trying to link to a foreign site, but we are converting all the images over to the site we are posting them on, because we found out while regular computers will display them, cell phone will not.

Now, back to the text and code showing up in the alternative box, we have tried deleting it or changing it, but when we save it, and reload the page, the image is gone.

We have even tried deleting the image from the post, (but not from the server) reloading it into the post, and run into exactly the same problem.

So, does anyone have an idea what is causing this problem?

Thanks

FTW