Hello Benne,
This issue has already been documented which you can view here:
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Cheers!
Using the deleted unused vars function can delete a var referenced in another BP. This occurs when for example the variable is not used in the graph of the bp you are deleting in, but this variable is still being referenced and in my case is just used to hold data (but is not in event graph). Should be simple to fix but might effect some people.
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