Mouse-over Stack Viewer Transparency

I want to set the Background Color property of the Main Map Mouse-over Stack Viewer to be semi-transparent. When I click on the color selector for Background color I see under the HSV and HSL tabs that there is a Transparency slider. While in the Edit mode of my module I can adjust this to what I want, then save the module and while still in edit mode open up a game, check it and it works just the way I want. However, after closing the Edit mode and then opening the module the background color is whatever I set it to with no transparency applied.

I like the transparency with a hint of shading so it’s easy to differentiate between the counters in the stack and those counters on the map near the stack.

Anyone have an idea of what I might be doing wrong? I can give you access to a copy of the module if you’d like.