GLTF2 is the new hotness when it comes to graphics interchange formats. Rightly so, but sometimes one is burdened with legacy systems or incompatibilities. The Better Collada Exporter of Blender 2.8 is broken as of 2019/06/27, and the blend shape / morph target support for GLTF2 in Godot is also broken. My workaround: export as GLTF2, then convert to DAE. This has a lot of things that don't quite work, including the originally desired blend-shapes, but it may be of use to someone out there.