Intellisense not working because of code creating columnstore index
In case it's already enabled, press Ctrl + Shift + R. That will update Intellisense with used database.

Sometimes, if the used database is not frequent, that does not work instantly in SSMS, but the above will update Intellisense.

In case of long script related issue, go to Tools>Options>. In there in on the left side, search for Text Editor>Transact-SQL>IntelliSense.

There is an item called Maximum Script Size. It may be 100KB`. In the drop down, change it to 5MB at least, or to Unlimited per your preference. After setting this, you need to close SSMS and start it again. Some older versions required a restart of the system. That should work.