Why are some emails not showing up in Outlook Desktop but are there in OWA?

This is due to the shared mailbox being in Cached Mode. Turn off cached mode to view all messages.

How can I use Outlook Search effectively?

Use the search bar with Current Mailbox selected for accurate results. Click the small arrow in the search bar to further filter results.

The New Outlook is not supported by Emailgistics due to specific functionalities still in development.

Resolve general Outlook-related questions and errors.

This is due to the shared mailbox being in Cached Mode. Turn off cached mode to view all messages.
Use the search bar with Current Mailbox selected for accurate results. Click the small arrow in the search bar to further filter results.
The New Outlook is not supported by Emailgistics due to specific functionalities still in development.