How is rotation information in metadata read by BigStitcher?

Hi All,
I have a custom mSPIM controlled by MicroManager and have started to use this to acquire multiview datasets. However when I try to fuse these in BigStitcher I notice that the rotation information is not read correctly from the metadata and fusion always fails. Similar data acquired using the Z.1 does seem to be correctly orientated and fuses well. Can anyone tell me what BigStitcher is looking for in the metadata in terms of rotation information so that I can add the relevant information to the metadata during acquisition?
Thanks,
Ben