Hi! By annotation records you mean examples in the data you're loading in? 10k really isn't much data at all so I don't think it's directly related to that.
The error here seems to happen when Prodigy is validating the first batch of the stream and then putting the generator back together. Apparently that error in itertools.tee is related to multiprocessing and raised because the iterator it creates isn't thread-safe...? I'm not sure why this happens in some cases for some generators and not others, and if it's a Python 3.8 thing or not, but we'll investigate!