in Amp3Body::normalize the caching of the waves seems to always start at the first event of the event array https://github.com/GooFit/GooFit/blob/master/src/PDFs/physics/Amp3Body.cu#L277
this might not be correct when doing simultaneous fits, as the events corresponding to a component can come later in the event array. This means that always the events of the first sample are used for caching values.

A possible solution would be to add an optional offset variable, which could be set in Amp3Body::setDataSize and then using thrust::counting_iterator<int> eventIndex(offset) instead