I wrote this before and it's still happening.
I configure the Magic mouse on MacBookPro to use a one-click on any word under any problem and pop up the Dictionary search which you normally do with your 3 finger tap on the Trackpad. It works in many apps very well but has difficulties working in Mail and PDFs. I have just tried it again and it just doesn't.
Instead, in Mail, it brings up the right-click context menu to say look up a word. In PDFs, nothing happens.
I remember the first time I brought this up, they were defiant that it works in all apps. A humble plea, please help me resolve this issue because I do believe that it should work in all. I use it so often whilst working.
I use Macbook Pro, Monterey, very up to date with all programs.