@leewei.
It looks that the most recent version of Excel (e.g.:Office 365, version 1908) is unable to load the Excel connector.
The message seen on the Add-In COM says:
"mscoree.dll : Not loaded. A runtime error occurred during the loading of the COM Add-in."
and the plugin doesn’t show.
Are you still able to manage the Excel Connector and provide udates to it?