Intro
I am aware that a part with the glass material is supposed to “hide” surface ui’s ect. But when the part is fully transparent this shouldn’t be happening. When there is a highlight instance parented to the glass part, disabled or enabled, it will still hide the surface ui behind the part.
Fully transparent glass
A fully transparent part with the glass material in front of a surface ui. As you can see, the ui is fully visible and the glass part is not affecting it.
With highlight
Now, we still have the same fully transparent part in front of the ui but this time, a highlight instance parented to it. This suddenly affects the surface ui even though the part is still fully transparent. You can see that the glass has a transparency of 1 by looking at it’s properties on the right.
With highlight that is disabled
Even if we disable the highlight, the effect is still present. You can see that the glass still has a transparency of 1 and that the highlight is disabled by looking at the properties on the right
Selecting
This also happens when you select the part while having “Outlines” as the selection style in studio.
It even reflects the sunlight when the part has a transparency of 1 and has a highlight instance parented that is disabled.
Demonstration Experience
Here is an uncopylocked place you can check out to see this bug for yourself. You can press the 3 dots in the top right of the experience and press “Try in studio” to copy it.
Thank you for taking your time to read this bug report! 
Expected behavior
I expect the highlight instance to not affect the effects of a glass part while its fully transparent. It should still show the surface ui behind it even when the highlight is enabled or disabled.