Many thanks to both. mcmc_trace and mcmc_rank_hist along with Rhat, n_eff show good convergence with no divergencies. However loo is not so happy. Possibly there are not enough factors?

```
Computed from 4000 by 633 log-likelihood matrix
Estimate SE
elpd_loo -282.7 9.3
p_loo 75.8 3.3
looic 565.4 18.6
------
Monte Carlo SE of elpd_loo is NA.
Pareto k diagnostic values:
Count Pct. Min. n_eff
(-Inf, 0.5] (good) 586 92.6% 1324
(0.5, 0.7] (ok) 43 6.8% 329
(0.7, 1] (bad) 4 0.6% 526
(1, Inf) (very bad) 0 0.0% <NA>
```

What does it mean and how to rectify it? Please note that the logistic regression is with GPs. Also, posterior classification accuracy is 0.89 and posterior balanced classification accuracy is 0.55, LOO classification accuracy is 0.94, LOO balanced classification accuracy is 0.55,