Sometimes applications can face internal issues that leads them to work differently. If you are facing the issue when Gmail is not receiving or sending the emails then ensure to force stop the Gmail app. It is essential because force stopping an app might troubleshoot the underlying issues. So, if Gmail IMAP not working then you need to force stop Gmail app to troubleshoot the issue. Proceed to settings and click on apps and notifications. From the list of available applications, click to Gmail. Lastly, click on force stop option present on the bottom of the Android screen. These are the steps that you need to ensure to smoothly troubleshoot the issue.