Concrete5.7 Stack Bug

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I added a stack to one page. The stack was showing fine. But when I edited the page, I got this error: Undefined variable: _bo. What does that mean? It does not tell error file / line number. The stack is just a normal html mark up.

Then I deleted my stack in the cms, I got another error on the page:

An unexpected error occurred.
Undefined property: Concrete\Core\Page\Stack\Stack::$ptID

How can it be fixed?