Hi Curt,
Thanks for sharing your experience with us.
We suggest you ensure you are using the latest version of Office.
Click File>Account>Update Now, see if there is any update available and install it. (The latest version of Office 365 for Mac is 16.23(19030902))
We'd like to confirm if you use the detailed steps below to install the add-in, if not, please clarify yours.
In Excel>File>Option>Add-ins>in Manage box, select Excel Add-in and click
Go>check Analysis ToolPak and click
OK
After the add-in is added, before closing Excel, if you go to File>Options>Add-ins, can you find
Analysis ToolPak displaying in the Add-ins list? And can you find Data Analysis appear in
Data tab?
If issue persists, we would appreciate if you share with us following information:
1.In Excel on PC, go to File>Account, please capture a full screenshot of
Product Information including Office version and channel info, we 'd like to check if we can reproduce the issue.
2.Regarding the symptom that the add-in disappears after they close a restart the program, could you share screenshots about it?
Best Regards,
Tina