This still looks like an error message, and the link to "troubleshooting" immediately suggests to re-install the addin manifest. However, in most cases, the "solution" is to simply open the plugin pane in outlook.

The underlying problem remains that we cannot differentiate between "plugin not installed (correctly)", and "plugin not currently active".

One improvement may be to make the troubleshooting link point to a popup with the following (in that order)

• information on where to find the addin in outlook, assuming it was installed correctly.
• information on what to do if the button shows (with or without broken icon) but doesn't work (T8023)
• link to the manifest installation procedure

Suggestions / wording welcome.