When zooming, the chart rotates and zooms in.
Gesture recognition may be frozen here. This can sometimes happen if there is not enough memory. Restart the app once, close it and close other apps that are open at the same time to clear memory.Please try to close all apps with the task manager (swipe in the screen from the bottom of the screen / use the button next to the home button on Android) and, in case the issue remains, also try restarting the device.
Now reopen only the NV Charts App. This should make more memory accessible to the NV App.
Also make sure that the device meets the hardware requirements and has at least 2 GB, better 3-4GB+ of RAM available.
Please let us know if we can assist any further with this issue.