Q: File Access Issue Since Upgrading to OS X Capitan

I have a file access issue that has begun only after updating the OS to OS X El Capitan 10.11.6.  I have an Excel 2016 workbook that has VBA code behind that processes (opens, read, copies) from other Excel books in a subfolder.  The first time I access a new file from the code, I am prompted to “Grant Access.”  In the past the “Grant Access” button was blue and I clicked it and away we went.  Now the “Grant Access” button is gray, and when I click it, the code aborts trying to open the file, indicating that access was not granted.  This happens whether the file is local or on a network share.  What might be my issue?  Thanks for any help!