The latest update has missing description / title on the node variable parameters which makes it difficult to know what it does.
Seem to be fixed in 2020.04.09.16.59 or previous.
I fond a workaround. Select another type from drop-down list, and select original one again.
Easier workaround: Press "Reload Graph" button
interestingly enough, if you create a node from the create new variable under setter/getter nodes, the descriptions show up.