I have installed the Salesforce CLI package and it is working fine from the terminal window.
I have installed the Salesforce Extensions package into Visual Studio Code and all looks fine.
However when I enter Command-Shift-P and type something like SFDX: Create Package I get a notification to install the Salesforce CLI package.
All the sfdx commands work fine from with VS Code’s terminal window.

I am at a loss as to what is wrong. 
I am running on a Mac and all the help articles are for Windows are direct you towards missing or incorrect Path statements. Not much help for a Mac user.

I have tried completely removing the SFDX package (via rm statements from terminal) along with removing the Salesforce extensions from VSCode. After reinstalling all this - same problem.

Any ideas or help would be appreciated.