I've had constant problems with anything related to the sunset/sunrise on my Apple Watch. This includes the complications, Solar watch face, and Astronomy watch face. None of the previous things I listed ever display the correct sunrise/sunset for more than an hour. Ever.
The complication seems to freeze at random times. The Solar face does not display sunrise/twilight/noon/sunset/dusk/etc, but instead displays the sun going across the sky at a fixed rate each day. The Astronomy face does not show the correct "phase" of the Earth, and shows that it is night time around 5:40 when in reality the sun doesn't set where I am until after 9.
I've contacted support several times, and have done everything I and they could think of to fix this issue. Hard resets, factory resets, unpairing and repairing, resetting settings on my iPhone, you name it. Extremely frustrating because this never happened before watchOS 1.0.1 and now it happens every. single. day.