Excel 2016 automatically converting formula to "array formula"

BilloCL I am not familiar with this happening. But if it happens to you, I will take a stab at an idea. After opening in 365, when ready to save, you might try specifying to "Save as" in a particular format. Worst case, you could save in "Excel 97-2003 Workbook" format which doesn't support newer features. Only you can determine whether this cure is worse than the disease! You could either leave it in this format, or, on the other computer, "Save as" back into the "normal" Excel workbook format.

Another possible thing to try is to write an Excel macro to remove the surrounding curly braces from all array formulas. Run this macro before saving (or have the macro itself finish by doing the save operation). I don't know if this will actually work, but it might be worth a try.