Rather than clicking and dragging the elevation raster in the 3D section, in ArcGIS Pro, we can define it as an elevation surface. Here's the documentation on that:
Hi Lauren Dreyfuss,
What is the workflow to simultaneously view multiple surface rasters in 3D In the scene view in ArcGIS Pro?
Say we have 2 or 3 different surface datasets and we want to compare them?
Following here. We have subsurface rasters that we need to drop below surface. However, all rasters are displayed under 2D layers and not a clue anywhere why we can't make them into 3D. We don't need to make elevation surfaces out of them because they are not surfaces. But we do want to display them with all 3D elevations as per values embedded in the pixels.