Upgrade Checker Action pack defaults to RUNMODE "BeforeUpdate" and the option to choose "AfterUpdate" is not available while using the Action Pack.
Packs: Upgrade Checker Action Pack
The "AfterUpdate" mode can be enabled by the following steps:
Edit the CYCK.PRPT.SELECT.UPDATE.TO Promptset (as you would see that the RUNMODE is set to read-only)
Simply uncheck the read-only checkbox and save the Promptest and you should be able to select Afterupdate within the RUNMODE upon executing the Action Pack.