I have been having an issue with some of our custom material appearances. In the past, when I would set a part to have a "Clear Blue PVC" material, the part would change to blue and the transparency would be set to make the part clear. The same is true for glass, acrylic, and all other clear materials in our material library.  Starting a few months ago, however, the Clear Blue PVC material no longer applied a transparency to the part, only the blue color, the part stays opaque.  However, all of the other clear materials in the library will make the part transparent when applied.  

I cannot for the life of me find the setting. Please help!

My Material Appearance for  Clear Blue PVC is set to "Blue Glass", which is transparent. If I directly apply the "Blue Glass" appearance to the part, I get a transparent part. But applied through the material, it is opaque.  See first image below.

Interestingly, we have another flavor of clear blue PVC called  "Clear Blue PVC-C", that uses the exact same appearance as the Clear Blue PVC (Blue Glass)  and it makes the part transparent just fine when applied.  See second image.   I feel there is setting for this, buried deep within the interface, hidden from myself and every other engineer here that has been trying to fix this issue.   There are a few other materials with this problem also.  Seems to have started when we transitioned to 2019, if that's anything to go on.   Thanks in advance for anyone who might have some ideas.

-Bret