Our Blender workflows enables textures being stacked on top of each other. In the images below you can see what I mean: we have baked an AO map in 1:1 scale and placed that on top of a tiled texture (brick wall) to avoid baking this as a large texture wrapping all around the facade.
If I were to guess, it seems to me that the glTF viewer is not able to read the map channels and therefore display textures without their attached map channel data. In the Babylon viewer, you can see that the loading displays correctly. Is this because the Babylon viewer allows several Map Channels? Unity for example only allows the two first map channels to be displayed (like most game engine does). Or do you belive there’s another problem?
Here’s how the texture nodes looks inside Blender (the custom node in the top is the one that displays the AO over the bricks)