Hi, Anthony. Sorry you’re experiencing this.
I wasn’t able to reproduce this for RSVP or WooCommerce ticket types, and this isn’t currently a known issue so I’d suggest following these recommended troubleshooting steps for your own site:
There might be some new updates available. Could you please make sure all your Modern Tribe plugins (and WordPress core) are at their latest versions?
Once you verify you’re on the latest versions, please test to see if the issue is still happening for you.
If it is, please follow our Testing for Conflicts Guide (basically switch to Twenty Sixteen theme and deactivate all plugins and custom code other than Modern Tribe plugins) and see if that helps narrow down the cause of this.
If it doesn’t, please enable WP_DEBUG and WP_DEBUG_LOG and share any debug messages you see while changing tickets quantity, navigating your site’s home page, events page, single-event pages, and any other of your site’s pages relevant to this ticket.
Then, please share your System Information (while in Testing for Conflicts Mode). That will give me a lot of extra information to help diagnose the problem.
You might also see if you can spot any console errors at your site. (If needed, you may reference our KB article Using Google Chrome Developer Tools.)
Let us know what you find out.
Thanks.