I have been using tooltips defined within teh Smart M.App, not at the data source level.
I have recreated the same issue as you, when I add a tooltip to the vector data and then display that in a map. I am using M.APPE 16.1.1276.0, as shown in Add/Remove programs.
This looks like a bug to me. I will log it in support.
The same syntax for vector tooltips is working in Desktop M.App.