I have created a D8 multi-site installation and spun two sites up, successfully. I am having issues with navigation through the administrative back office, as, if I click on any of the links, I get a "not found" error for the page, unless I add "/index.php" to the URL. Thus, to navigate to the "Configuration" section, I need to supply the URL "mysite.example.com/testa/index.php/admin/config". I am pretty sure that my issue exists in my Drupal .htaccess file, but, I've followed the instructions for the multi-site install, pretty much to a tee, so I'm at a loss of what I might need to add or adjust to repair proper site functionality. Any assistance would be greatly appreciated!