I have found on some touch-switch lamps, that reversing
the hot / neutral plug orientation makes a big difference.
But that may not be the best idea for wet locations.
Might check that whatever the "touch electrode" is, on
the module, has a nice bright connection to whatever
is supposed to be "touch active" (whole body, some plate
or section of the lamp-stack, etc.). And that the earth /
neutral connection, has not. From my occasional poking
it seems these sensors work by imposing a "line hum"
onto the touch-point and detects how much your body
loads that down. Which fails if your body doesn't much
represent a low-impedance-to-earth for reasons of
body or earth or earth-substitute qualities.
And to that note you might do some bench poking, like
attach a 0.01u capacitor to earth and poke the "touch-
plate" with the other end, to see if -some- triggers work
or none at all. Maybe put an AC DMM from touch plate
to earth and see if it's got meaningful "live hum" and if
depressing that hum-level with shunt-to-earth (R, C, RC)
results in actuation, and then how your body contact
compares.