You need "tap" contacts closer to the transistor active region.
DRC should highlight the device in question. You may have
used an unreasonable geometry device (for noise / matching
reasons) which makes <20um gate*active - tap impossible,
this might make you change fingering etc. For analog where
possible I prefer guardrings to lonely "tap" contacts, "taps"
that pass latchup do not suffice to corral substrate noise
/ diffusing carriers from elsewhere.
Now, I would expect that your PDK documentation has a
decent discussion (with cartoons) of the tap / latchup
rules, which you could read.