This is hardly descriptive. Let's explore this like a deposition:

1. When does it get uncomfortable? As soon as you set off, or after a certain distance and/or time.
2. Do you slide forward or backward on the saddle?
3. Like veganbikes asked, have you ever had a fit with this saddle?
4. If not, have you tried positioning it differently?
a. If you move it forward or backward by 5 mm, how does it feel?
b. If you change the tilt by a couple of degrees, how does it feel?
5. Have you ever felt comfortable on another saddle? If so, what bike did you try that saddle on?