I’m currently having an issue in Roblox where lighting from lights circling around a glass part are not evenly distributed across its surface. Instead, the result are many tiny dots. This result occurs with every lighting type.
In addition to trying what @Scottifly said, I would try changing the Glass material to something similar like Plastic or SmoothPlastic, and seeing if this helps. Keep in mind you can get them to look very close to glass by changing their transparency, color and reflectiveness properties, but the light will bounce off those materials differently than it does glass.