Custom PHP Application in subdirectory of WordPress not working

I have a PHP application that was working perfectly in a subdirectory of my site. Then I moved WordPress into the root directory, so my app is basically in a subdirectory of WP. Once I figured out some session file problems, I had it mostly working except for this bit. The app has its own htaccess file, and I’m sure that’s the problem. I use mod_rewrite for a lot of things in the app. The problem occurs with these rules in the app’s .htaccess…

RewriteRule ^simple([/]*\S)?$ view_simple.php$1 [L]
RewriteRule ^simple/(\S)?$ view_simple.php$1 [L]

Going to works fine, but when I try going to I get a WordPress 404 error, rather than view_simple.php utilizing variable=value like it should

Like I said, it worked before I put WordPress in the root directory. Nothing in the appfolder changed.

Here’s the pertinent part of the directory structure…

Any ideas on why this would happen? Is this the right place to post this question? An help is appreciated, as this is currently on a production website. :slight_smile:

Thanks in advance!

I really don’t want to resort to using the actual filenames, but I can if I have to. If I go to the url, but use the full filename (view_simple.php?variable=value) it works fine.
Can you help me avoid that fate?