Thank you very much for your help, I actually identified the problem: in my wp-config file, and in my php.ini and index.php, the default charset was set to ‘utf8’ and not ‘utf-8’. Changing everything to ‘utf-8’ solved the problem.
I did read in another thread that ‘utf-8’ isn’t the proper way to name the charset in certain places, but so far this has fixed everything.
Here’s the error message I was receiving, for posterity:
warning: htmlspecialchars(): charset ‘utf8’ not supported, assuming utf-8 in :\wamp64\www\wordpress\wp-content\plugins\jetpack\_inc\lib\admin-pages\class.jetpack-react-page.php on line 192
