There are a couple of vector tile basemaps that appear to have issues in Runtime (100.2 or 100.3), but work fine in ArcGIS Pro. The problem is that certain vector tile layers/basemaps with a little transparency show the blank, grey-gridded background behind them (see below.)
I am wanting to use the Charted Territory basemap in Runtime . I've modded your GITHUB sample (arcgis-runtime-samples) under 'Layers/ArcGisVectorTiledLayer' as shown below and the resulting image is also below. The same result occurs if I use the direct .json ref to the layer (https://www.arcgis.com/sharing/rest/content/items/1c365daf37a744fbad748b67aa69dac8/resources/styles/root.json)
Does anyone know any fixes for this?