It turns out that the issue was with the AJAX calls. AJAX will not let you call a different domain for security reasons, so setting the SERVER_ROOT
to a different domain than my masked domain was failing (silently btw, blank error message in phpgrid). So I was forced to move the phpgrid files and folders into the webroot and change the SERVER_ROOT
to a relative path.
A simple fix although I would have preferred to keep the files in the vendor
directory.