pauldack on "[Plugin: WP-Spreadplugin] 502 Error"

Any idea what's going on here?, just keep getting a 502 error.

Tried disabling all plugins and reverting to the default WP theme.

Tried another another site with different host, same problem.

Appreciate any pointers.

gsdcom.wpengine.com/test

https://wordpress.org/plugins/wp-spreadplugin/