Jason W. wrote:

The message posted to the 8/15 thread did not work. The solution
presented earlier was as follows:
Create a temp category, select the newly imported contacts, add them
to that category. You can remove them from the category right away.
The idea seems to be that they need to be "modified and saved" after
being imported for the b'day-cal thing to happen.

It appeared to work for new items created in the folder but not the
transferred ones.

That's one of the reasons why you never use import and export for
transferring data from one Outlook to another. Import/export loses data.
--
Brian Tillman [MVP-Outlook]