This PDF is, I think, very informative.
Of particular interest, please refer to Snubber followed by Off-state leakage current on 'page 7 of 16' ("2-16"):
SSRs always have off-state leakage currents. The thyristors, control circuitry and
snubber network all supply small off-state currents, which usually total from about 1
to 10 mA rms.
These leakage currents should be taken into account when either indicators are used,
or the circuit may actually be touched, say for servicing. A resistor across the indicator and a line safety breaker are the standard means by which these limitations can be overcome.
ssr.pdf (954.9 KB)