there are no Bezier handle on the keyframes themselves. The option to separate the x and y components is greyed out
position keyframes don't get bezier handles unless you separate them and you can't separate any property other than transform position of the layer.
I have unchecked "Use Linear Vertex Paths" under Mask Interpolation.
this is not related to bezier handles for position, but to the way the vertices of a mask can move (straight line or curved)
Even using the Convert Vertex tool does not work
how are you using it? if you are using it to convert temporal linear keyframe to auto bezier - it works in the graph editor
you might want to get information by reading the help files and not the forums.
I have read lots of help files and will continue to; trying to find the detail you're looking for is often a needle in a haystack, which is why I am glad communities like this exist.
Either way, thanks for the input; I appreciate your time and effort answering my question!
Glad to help. Thanks for the feedback.