I’ve honestly never heard of any kind of issue like this. This seems like some kind of issue with your WordPress site or your setup there on your server with your database. Why I say that is because the theme doesn’t actually do anything custom in saving this data, but maybe explaining this to you will help you to solve your issue or recover your data.
The framework registers a custom post type called “tb_layout” and then each custom layout you create is a new post of this type. Then when you configure your elements, this is saved as a post meta (also known as “custom fields”) to that post.
Realistically for WordPress, this is the same as if you created a new standard post and then added custom fields to it. So that’s why I’m having trouble making sense how you say it “crashes”. The only way for that screenshot to be possible is if all of the meta data for those posts were somehow wiped clean in your database?