E_WARNING: Illegal string offset 'users_can_register'

Have a big problem with this plugin. I am using this plugin on a very high scale site. It is wordpress multisite and using memcache. I keep getting the following errors in my logs.

Error message
E_WARNING: Illegal string offset 'users_can_register'

in get_site_option called at <path>/web/wp-includes/option.php (990)
…gins/better-wp-security/modules/free/hide-backend/
class-itsec-hide-backend.php (123)
in ITSEC_Hide_Backend::execute_hide_backend called at ? (?)
in call_user_func_array called at <path>/web/wp-includes/plugin.php (505)
in do_action called at <path>/web/wp-settings.php (353)
in require_once called at <path>/wp-config.php (180)
in require_once called at <path>/web/wp-load.php (34)
in require_once called at <path>/web/wp-blog-header.php (12)
in require called at <path>/web/index.php (17)

Error message
E_WARNING: Illegal string offset 'users_can_register'

in get_site_option called at <path>/web/wp-includes/option.php (990)
…inspirewp/web/wp-content/plugins/better-wp-security/core/
class-itsec-files.php (418)
in ITSEC_Files::file_writer_init called at ? (?)
in call_user_func_array called at <path>/web/wp-includes/plugin.php (505)
in do_action called at <path>/web/wp-settings.php (237)
in require_once called at <path>/wp-config.php (180)
in require_once called at <path>/web/wp-load.php (34)
in require_once called at <path>/web/wp-blog-header.php (12)
in require called at <path>/web/index.php (17)

I believe it is related to the following bug in core here https://core.trac.ww.wp.xz.cn/ticket/31147
But it only seems to be happening with this plugin…….

https://ww.wp.xz.cn/plugins/better-wp-security/