You overwrote your posterior when you called
posterior_f = pm.sample_posterior_predictive(posterior_f)
You can do
posterior_f = pm.sample_posterior_predictive(posterior_f, extend_inferencedata=True)
You overwrote your posterior when you called
posterior_f = pm.sample_posterior_predictive(posterior_f)
You can do
posterior_f = pm.sample_posterior_predictive(posterior_f, extend_inferencedata=True)