What if I don't specify any parameter 'observed'?

Even if you don’t show the original model, can you show a minimal example? This works fine

with pm.Model() as m: 
    x = pm.Normal('x', 0, 1) 
    trace = pm.sample() 
pm.summary(trace)
    mean     sd  hdi_3%  hdi_97%  mcse_mean  mcse_sd  ess_mean  ess_sd  ess_bulk  ess_tail  r_hat
x  0.039  1.025  -1.814     1.99      0.025    0.018    1638.0  1638.0    1640.0    2601.0    1.0

If your prior samples don’t correspond to your priors it must be because your model has some implicit constraints somewhere