It seems that when I call a UDF in an XLAM file, the path to the XLAM file is embedded in the spreadsheet. When I open the spreadsheet from another machine (which has the same XLAM add-in installed, just installed to a different path) then Excel complains "This workbook contains links to other data sources..." This doesn't seem to be a problem with UDFs in XLLs. Is there a way around this?
This behaviour is a consequence of the way Addin UDFs are implemented in Excel.
There are 3 approaches to alleviating the problem:
Use an installer that forces a particular path
Add some code to the XLAM that inspects Links for each workbook opened and if the link is to your XLAM but in a different path it does a find and and replace so that the path is corrected.
Convert your XLAM UDFs to XLLs (if VBA convert to VB.Net and use Excel DNA or Addin Express to make a VB.Net XLL)