You may see the Elementor popup closing automatically when you upload a file in the Everest Forms plugin. You can troubleshoot this with the following steps.
- Go to Templates > Popups.

- Edit the required Popup.
- In the Editor screen, click on the Settings button on the bottom-left.
- Now, go to Advanced Settings.
- Enable the following options.
- Prevent Closing on Overlay
- Prevent Closing on ESC key

- Click on Update.
You will be able to fix the issues with the File Upload field now.