We're seeing more and more reports lately of Inventor 2020 failing to start after displaying the Inventor 2020 splash screen.
Upon investigating further, we've proven that Avast anti-virus software is interfering with the Autodesk software startup process and preventing the app from running.
Unfortunately, either disabling or configuring Avast doesn't appear to have any difference, and it's our recommendation that you speak with your IT Administrator regarding the removal of Avast anti-virus software.
After Avast has been uninstalled and the computer restarted, Inventor should launch as per normal. (The user may also be prompted for their Autodesk ID upon launching Inventor too).
Autodesk is aware of this issue, as reported here;