There are several scenario's in which an open pop-up form refuses to close on a Close Form action in a microflow. Specifically, I am using a blocking pop-up that prompts a user to login when accessing a microflow. This pop-up did not contain a dataview at first (as it is not necessary), but then it wouldn't close, ever, unless I clicked the X in the corner. Then I added a dataview to it, and it now closes if I press a button with a microflow + close action behind it. It does not, however, close upon logging in, using the Login Form widget inside the pop-up. It just reloads the starting form and logs the user in in the background. Even if I add a 'Close Form' action to the start-up microflow, it simply doesn't. It seems the application 'forgets' there is a pop-up open and attempts to close the in-content form in the background. Why? (non-blocking pop-ups seem to close more consistently, but I can't use those, since they refuse to open in the centre of the screen for some reason).
I think I have already a ticket for this (or very closely related) 8641 release date is for 3.0.1.