This issue often happens when a fresh install of the document outlook plugin or when outlook is reinstalled or updated.

Outlook will attempt to improve performance by disabling any plugins that cause the program to load slowly, causing it to disable the plugin, even if it is set to active in the add-on options. This is a known behavior and is due to how Outlook works.
You can resolve this issue and allow the Axcess tab to show in outlook with the following steps:

1. Open Microsoft® Outlook®.
2. Click File.
3. Click Manage Add-Ins.
4. You should see Cch.Pfx.OfficeAddin.Core.Outlook in the list as a detected problem.
5. Expand the "Options" arrow.
6. Select Always enable this add-in.

if you click OK and go back to the main outlook screen, you should see the Axcess options showing again.