ESTK doesn't show any CC apps (except itself)

Hi all,

I have CC 2019 (inc. Photoshop, Lightroom).

I've just installed the ExtendScript Toolkit CC from the CC app but when I run it, all I have in the target application dropdown is the tool itself i.e. "ExtendScript Toolkit CC". No other apps. How do I link this to my Photoshop CC 2019?

FYI I'm running Windows 7 64bit.

Thanks

Steve