I'm trying to use an Esri Basemap as VectorTileLayer in a custom JS application, built on the 3.19 API. I've adapted this sample for my application: layers_vector Sample in ArcGIS Sandbox
In the sample, the layer looks fine as you would expect it. I've also downloaded the sample to host it from my local IIS, and everything's alright. As soon as I put the VectorTileLayer into my own application, the tiles appear with red boundaries and big labels with numbers (seems like the tile location or ID) on the top left corner of each tile.
Here's a screenshot, with the sample (as expected) on the left and my custom app (with unwanted borders and labels) on the right side:
I would understand that this could probably be defined in a Vector Layer Style, but I've used the following 2 styles and also the direct reference to the VectorTileServer both in the sample and in my custom app - the effect is always the same!
var vtlayer = new VectorTileLayer("https://www.arcgis.com/sharing/rest/content/items/bf79e422e9454565ae0cbe9553cf6471/resources/styles/root.json");
I don't think that it's anything connected with CSS (I don't even see the single tiles as objects in the DOM tree), and I've stripped down the code of my custom app so that only the map and the VectorTileLayer are being used, as it is in the sample - no luck.
Any ideas what this could be are highly appreciated!