Closing wrong form?

On my form (A) there is a button. Clicking it opens a form (B) editing a record. ‘Save’ button checks data on that form (B), and does the ‘Close form’ activity. The ‘Save’ button is deactivated and the form is not closed. However, form A is closed! This behaviour is new for me. What went wrong?   Mendix studio pro version 8.18.0.
1 answers

Can you reproduce this behavior in other forms? And if you generate an overview and NewEdit form by rightclicking an entity in the domain model, does this behavior occur as well?