If I run Share As Web Layer in ArcGIS Pro 2.1.2, and choose vector tile as my layer type, the resulting hosted vector tile layer gets successfully created in ArcGIS Online, but it appears empty. The selected scale range is correct, and you can zoom to the layer but it is as if the symbology is completely transparent. I analyzed the layer, and there were no errors reported during the process.
If I create the vector tile layer by using the Create Vector Tile Package, then Share Package, then publish the layer that works as expected.
I would really rather use the Share Map as Web Layer tool instead of the Create Vector Tile Package tool which requires several more steps.
Is there something I am missing? I am testing this on an extremely simple polygon layer with no labels and no complicated symbology.