Debugging a plugin or theme conflict should be done on a staging site if possible.
While you're debugging (depending on the type of error), you should have the JavaScript console or PHP error log in view in real-time.
Make sure you have a recent full backup of your site (live or staging) and theme settings.
Deactivate all your plugins except for MonsterInsights. If you have to do this on your live site, pick an off-peak time.
It's a good idea to select the active plugins filter near the top of the Plugins page and print that to a PDF file so you know which plugins to reactivate when you're done.
Once that's done, with only MonsterInsights enabled, try the following (using a JavaScript error as an example):
- Purge any server/WordPress cache.
- Open an incognito/private browser window.
- Load your site in the private window with your JavaScript console open (https://wordpress.org/support/article/using-your-browser-to-diagnose-javascript-errors/#step-3-diagnosis).
- Check your JavaScript console for errors.
If the JavaScript errors are gone, that means there's a plugin conflict.
You can start enabling plugins one by one until you see the JavaScript errors come back in the console.
The last plugin you reactivated before you saw the JS errors come back is almost always the cause of the conflict. You'll need to report the issue to the plugin's author.
If the JS errors still show up with all plugins deactivated except for MonsterInsights, try switching your theme to a default WordPress theme (Twenty Twenty or Twenty Twenty-One, for example).
If the JavaScript errors disappear after switching themes, then there's a theme conflict. You should contact the theme's author or think about using a different theme.