There are no file options for saving from the VFB (bit depth, compression, alpha etc. ) at the moment. For saving to TIFF, it creates transparency rather than an Alpha when saved from the VFB at the moment. Both issues are known and tracked internally at 312925631. This is due to their being two save mechanisms, the native C4D save option, and our save option from the VFB (it is not simple to integrate with the C4D save dialogs unfortunately - this is also why CXR is not in the C4D native options).