Fatal error

I was testing with Verity and purchased the upgrade to Verity Pro (1.7.3) to start developing in the new theme. With the theme enabled, hitting Customize seems to consume all memory and causes a crash. All plug-ins are disabled, and I verified that things work as normal with the default Twenty-Seventeen theme as well as Verity (non-pro version). I tried this on two different hardware configurations and systems (FreeBSD, Linux) running different versions of Apache (2.2, 2.4) and PHP (5.6, 7.0) and had the same results on both systems. Here is the error: Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 72 bytes) in /[my-web-directory]/wp-includes/meta.php on line 837