Hello @lesliex,
First, please save all permalinks (once again) from WP Settings > Permalinks.
Then if your issue persists again, for troubleshooting, please deactivate all your plugins and let the MEC remain active only, set your theme on default, then reload the page. If the issue was solved, then activate your plugins one by one and your theme, refresh your page and check to see which plugin is causing the issue.
Also, we need more info of your website and server. Please go to wp-dashboard > tools > site health and in the Info Tab click on “Copy site info to clipboard” to save all the required info to the clipboard: https://i.postimg.cc/TPrGsHXY/image.png then go to this link https://pastebin.com/ and paste the info here. Finally, get an info link and send that to us here. With that, we will be able to help you more.
Please keep us informed,
Best Regards