UI Corner removing itself

It’s impossible to edit my GUI’s, because everytime I click on it, the UI Corner removes itself.
https://gyazo.com/43137028907ce1acf2b8547a423c2f8b
Any solution?

That is a very strange issue. It could potentially be a bug with the Studio application itself.

You don’t have any plug-ins selected, right?

No, I’m adding the UI Corner manually