Block Reference incompatible with Deploy

I am aware that it's not really your responsibility to make sure that this module works with every contributed module out there, but I figured it wouldn't hurt to ask for some help.

I'm trying to deploy a node that has a block reference to a target server using the Deploy module, which depends on Services. Here's the behavior I see...

Deploy a node with a value in the block reference - works.
Deploy a node with an empty value in the block reference using autocomplete widget - works.
Deploy a node with an empty value in the block reference using select widget - fails with "invalid option".

I've been stepping through the code but can't figure out where it's failing. Can you point me in the right direction?

Thanks for making an awesome module. I realize this is a special case.