For my local copy of your site I installed the duplicate and made no changes of any kind, simply looked through the Views to see if I could spot the same problem with the HTML entities, and then to check using the Block Editor the only change I made was to update the settings for the news post type so that it used the block editor.
I'll ask the devs in my meeting with them in the morning if they have any insights.
I could do that, but I don't have the log-in credentials (just the site duplicate), so let me set up a private reply for those.
If it were the case that some scripts are being blocked I would expect to see JS errors in the browser console along with 404 messages for such scripts.
So, I can see the issues on your site, with the HTML entities when editing the View, and with the Blocks editor not working correctly.
But... I can still see the problem with the Blocks editor when disabling *all* plugins (including Toolset) and switching theme to twentynineteen, so there seems to be something fundamentally wrong with this install.
I re-installed WordPress and that didn't help.
It's a busted install, somehow.
Rather than expending too much energy trying to establish why, if possible I would spin up a new server, verify that it works (i.e. the Blocks editor works as expected), and if so try using All-in-One WP Migration to export then import a copy of the current site and testing again.
I expect that whatever has broken the Blocks editor is likely responsible for the problem with Views, too, and if you fix the former the latter will hopefully take care of itself.
Well... feeling kinda embarrassed and facepalming myself but...
In the user profile, "Disable the visual editor when writing" was checked.
I am positive I checked to see if this was the case (more than once)!!! Unchecking the box solved the problem.
****But****
The good news is that this was also the cause of the error with the HTML code for an apostrophe showing in the content template of a view - so presumably this could be fixed in the future.
