There's a few quick troubleshooting steps you can do:
- Check and see if you're including jQuery Migrate. If so, in your layout.master there will be a line like this:
<portal:ScriptLoader id="ScriptLoader1" runat="server" IncludeJQueryMigrate="true" />
Keep in mind there are probably going to be other tags on the ScriptLoader as well, but that one in particular can fix some compatibility issues if you enable it.
If you're not sure how to look for script errors, you could also paste the URL here (provided it's a public site), and I'll take a look at it.
Hope this helps,