Merging with an Access table has many issue. For instance Word has to open another instance of Access to perform the merge. This cause Access to get loaded twice.
I have found it best to avoid ever letting Word use an Access database as a merge source. Instead I export the data from Access to a Word merge document. Have Word use this as the merge source. I have not ever had any issue with this method with any Word, Access and Windows version combination.
Boyd Trimmell aka HiTechCoach (.com)
Microsoft Access MVP Alumni 2010-2015