Hi @James R. Sick,
Currently, Power Query on Excel for Mac only supports absolute references to a data source. Dynamic references or parameterized data sources are not supported on Excel for Mac. If you are trying to create a parameter to refer to a connection string, you will need to create a separate connection for each value of the parameter.
You may encounter some error messages such as "on-premises gateway is required" or "not a valid absolute reference" on Excel for Mac when you try to use features that are not supported. This is because some Power Query functions require certain features that are not available on Mac, such as On-premises data gateway for Windows Authentication.
Also, I would suggest going to this Microsoft feedback portal for Excel: https://feedbackportal.microsoft.com/feedback/forum/c23f3b77-f01b-ec11-b6e7-0022481f8472 and raise a thread there. The product team actively monitors feedback there and will make improvements in the future.
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