Several times when trying out Falcon caching I've found my site down due to a truncated .htaccess file.
I've taken out all rules but that required for WordPress to run.
It seems to happen when a deny IP rule is added to or removed from the top of the list by Falcon.
It might relate to running WP in multiuser. I've removed or disabled any plugins that could alter the .htaccess file.
I've added several lines of # marks (doubling in length of 1 thru 2048) to see if I can catch if it's random or specific number of lines or characters.