Scott, if that pattern was indeed silk screened on the mesh, most of those inks are UV cured....I know you said you've kept it outside, but have you let it hang in the sun a couple of days......Maybe curing that ink a little more would help.
My vest isn't mesh but more like cotton. Not sure what the material is as I haven't hadany stand time with it
Im pretty sure it got quite a bit of sun on my porch over the fall and winter up until a couple weeks ago. It isn't an enclosed porch and I had it hanging near the end of a rafter.