I don't know how you did it before but try this. Press ALT + F11 to open the Visual Basic Editor, select Module from the Insert menu then paste into the white space on the right
Function ConCat(r As Range) As String
ConCat = Join(Application.Transpose(r), ", ")
Press ALT + Q to close the code window then in a spare cell enter a formula like
to concatenate the values in A1 to A100. Then copy that cell and paste into Word.