Android system bars doesn't hide again after input in fullscreen app


I’ve got an app that uses the Fullscreen setting in config.xml, but when it’s deployed to an Android device (Nexus 5) the top and bottom system bars doesn’t hide after inputting data. I’ve attached a screenshot of the form during editing and also one after when the bars remain. The only way to get rid of them is to drag down the top thingy and then close it again, it’s like that’s triggering Android to hide it. Any ideas as to what could cause this?

This is the form (which is inside a modal).

This is the screen after the Save button is clicked, which performs the save and hides the modal again.