Commiting sparse texture's mipmaps

I get a strange problem with commiting a sparse texture’s mipmap tail. All is fine while level<NUM_SPARSE_LEVELS_ARB, however once I try to commit the tail, everything crashes and burns and I get an access violation (nvoglv32).
According to the spec, glTexturePageCommitmentEXT with level == NUM_SPARSE_LEVELS_ARB is legal. The offset is 0, and the size is the actual level size (size >> level).

nVidia GTX 980 with latest drivers, 4.5 profile.

Assistance welcome!
Thank you