Hi,
sorry for not getting to you earlier. The model is a bit too complex for me to debug quickly. I’ll note that most of the advice at Divergent transitions - a primer will apply. In particular, it would be helpful to try to simplify the model until the issue disappears.
My first guess would be that since the init_scores and tau enter the likelihood only through score_diff you have a location non-identifiability, i.e. that adding the same constant to all elements of team_scores will give you exactly the same likelihood (as the constant cancels out). The solution would then be to either enforce a sum to zero constraint (see e.g. Test: Soft vs Hard sum-to-zero constrain + choosing the right prior for soft constrain) or to take one round/team as reference and fix their scores to 0 (or other constant), so that you’ll have one less row/column in the tau matrix… I am being a bit vague as I don’t understand the model well, but I hope the general idea is clear.
Best of luck with your model!