When you face issue using Postman either with startup or with its functionality, please provide the following logs to help@postman.com to find the root cause of the issue.
1) Network Logs: Navigate to View > Developer > Show DevTools (Current View) and View > Developer > Show DevTools (Shared), click on the console Tab and provide the screenshot of the tab.
2)App Startup Logs: Navigate to View > Developer > View Logs, provide all the files as zipped.
This document here should help you know more on the same.