Tried this in Worksheet Functions and didn't get a response. Any MVPs around?
-----------
General: Why will links created between two Excel spreadsheets NOT update
properly when the target Excel file is embedded in a PowerPoint chart/file? I
created the original set of files on my desktop and then uploaded to a
SharePoint site?

Specifics: I linked cells between an Excel source file and an Excel target
file. I then embedded the target file in a PowerPoint file/chart. As
expected, when I change data in the source file, the data changes are linked
into the target file that exists in the PowerPoint file. Works great!

But I really want to place all three files together in a SharePoint site.
When I change source data in the SharePoint file, the Excel target file still
updates OK; the linkage was preserved when I uploaded the two Excel files.
However, the (target) Excel file embedded in PowerPoint does not update. I
looked at the linked cell in the embedded Excel file; it is still pointing
back to the original target file on the Desktop.

Guess this makes sense if uploading a PowerPoint file from Desktop into
SharePoint does not preserved embedded Excel links.

So what do I do? Is it necessary to create all the linkages from within
SharePoint? Can I safely move the files back and forth between SharePoint and
Desktop (or anywhere on the PC) in a way that the linked cells are updated as
desired?