Quote: "This would be far simpler if the the download link appeared on my TGC account or even better, if there was a download button on the store itself."
This won't be the case I am afraid. The store is intentionally written this way to enable better integration in future as well as asset protection for artists, we won't be changing it.
As for the bug I am afraid it is a case of waiting for V1.007 to arrive (not long), this fixes the issue we had internal devs with this issue so we do know about it in V1.006
Windows 7 Pro, Intel i7 3.8 GHz, 16GB DDR3, NVIDIA GTX 780 4GB Superclocked