It happens that R D S formulated :
Much ****ing about later there's a sink in the worktop, on the wonk slightly,
too close to the back so that the worktop can't quite reach the wall unless
we severely *******ise the rear of the base unit. But it will certainly do.

Did he waterproof the cut edge of the worktop as well as seal the sink
to the worktop? Many pros do the later, but miss out the prior with the
result that any moisture bursts the worktop eventually.