I suspect the Close Page action is trying to close the page that launched the microflow.
One approach to get the behaviour you need could be to split out the code after the Show Page action into it's own Nanoflow. Then, on the popup page, use the Events widget (Platform Supported) to trigger the new Nanoflow when the page is shown.
https://marketplace.mendix.com/link/component/224259?ste_sid=b47a458c3e83f9356790a3c1134f8225
I hope this helps.
To resolve your issue use show page in that select your desired page and on close page action do single or multiple according to your requirement.
I Hope this will solve your issue :)