Toonboom vectorized pen is transparent?

Whenever I draw lines, all of the same opacity, once the opacity is lowered you can see all the other lines, as if they werent the same opacity at all… This makes shading, colouring, and everything extremely hard.

Does anyone know a fix to this?

Note: Flatten doesnt work

Seems to me that what you are seeing in the image is exactly what you should be expecting by lowering opacity.

Once you lower opacity any lines that overlap will be doubled in opacity and appear darker than those that are a single layer.

What are you attempting to accomplish by adjusting opacity?

If you want a lighter line and to retain line consistency try changing to an opaque gray.

If you are trying to simulate pencil sketchy lines, they are probably more opaque than you realize. They thicken more than they solidify.

Dialing towards transparency (away from opacity) results in more of an effect characteristic of watercolor where any overlapping strokes appear darker, more saturated with pigment and so on.

The layer itself had a lower opacity, and the lightbox did that with the rest of the layers however it had an opacity of 100 percent.

It does that to all my lineart, colours, all of 100 percent opacity and I dont understand why.

Again, what you are seeing is the normal result of adjusting opacity.

There is a tool called Top Light which has several sliders you might try playing around with to see if you find an opacity target you prefer working with.

Documentation > Reference > Dialog Boxes > Onion Skin and Light Table Transparency