Lineweights not showing up

I have a block that represents a tree. It consists of a circle with a crosshair in the center. All three items are on layer 0, all attributes set to to "by layer", no thickness/width assigned to anything.

I want the trees to read with a thickness to them. I used to have a thickness assigned to the circle, but when I scale the block up or down the thickness obviously changes with the scale. Not good. So, I've assigned the layer the blocks are on a lineweight. I've tried several different thicknesses, and they all show up just fine in model space, but not in paperspace.

I've checked ltscale, msltscale, psltscale. There are no viewport overrides on the layers these blocks are on. The viewports don't appear to have any overrides on them. I have show/hide lineweight set to "show."

What am I missing? I don't like to manually assign lineweights to individual objects; I prefer using layer settings. The only thing I can think of is that the plotstyles my company use are color-driven (magenta is the darkest, cyan the lightest, 8 is gray).

I'd appreciate any help. I know I'm missing something...

When you say thickness, you mean lineweight, right? Thickness is a 3D thing, thickness along the z axis. ltscale, msltscale, and psltscale have nothing to do with lineweight. They control how long the pieces of the lines other than continuous are plotted or displayed.

Paperspace doesn't show the lineweights if you don't have "Plot object lineweights" checked, or "Show plotstyles" checked. When using a color dependent plotstyle, don't check "plot object lineweights" unless the entire drawing has been assigned lineweight properties, either directly or by layer.

Using a color dependent plotstyle will ignore the lineweight you assign to the layers or object properties and plot the lineweight that has been assigned within the plot style table, unless you override it by checking "plot object lineweights".

If there are no clear office standards on using the color dependent plotstyles, you will have to open the plotsyle editor (click on the button next to the name of the plotsyle, and look for a color/lineweight combination that most closely suits your purpose.