unable to access gridfs in a different database

I've been accessing my other database just fine using db_alias for most collections that do not contain FileField() or ImageField() fields. However, for collections with FileField() or ImageField() I have not been able to access the file in the other database. Does db_alias not properly link fs.files and fs.chunks in the other database? Must one somehow add meta = {"db_alias": "OtherDB"} to fs.files and fs.chunks?

class File(db.Document):
     file = db.ImageField()
     meta = {"db_alias": "OtherDB"}

for i in File.objects.all():
     print i.file          # Shows '<ImageGridFsProxy: (no file)>'
     print i.file.length   # Shows 'AttributeError'

Start by reproducing the File model with db_alias set to OtherDB and inspect how FileField/ImageField access GridFS through fs.files and fs.chunks. Check the ImageGridFsProxy path, and consider the issue resolved when file access and length work from the aliased database.