Hi, I am not sure, the WP GoToWebinar has been really well designed, it uses standard WordPress hooks to implement things like CSS and Javascript onto the relevant pages. There’s nothing non-standard with how the plugin is designed/implemented.
All I can suggest is in W3 Total Cache try clearing the cache, and perhaps tweak the settings to maybe turn off things like minification/combination of scripts. WP GoToWebinar implements it’s own cache but this is not a frontend cache, it’s a server-side cache (once again implemented to best practice) so it really shouldn’t interfere with caching plugins unless W3 Total Cache is doing something funky. I have used WP GoToWebinar with caching plugins before without issue – but not specifically W3 Total Cache.
What you can also try doing, and I should have mentioned this a lot earlier is to turn on debugging by adding: define( ‘WP_DEBUG’, true ); to your wp-config.php file, documentation here: https://codex.www.ads-software.com/Debugging_in_WordPress and then activate WP GoToWebinar and hopefully instead of the white screen you will see a white screen with an error message. Let me know what that error message says and maybe that will give more insight into the specific issue. Thanks,