Hi, Whirly Fizzle! I am using this version, I updated to it many days ago.
Firestorm 6.0.2.56680 (Firestorm-Releasex64 64bit)
This is how I see a tattoo texture saved with 49% opacity in Photoshop. The transparency shows up fine: The texture is being applied on all sides of a prim, as a local texture.
Then I repeat the same process, but saving the same image with 55% opacity in Photoshop. Once applied on the same prim, the tattoo looks completely solid, as if I have saved it with 100% opacity in the editor.
I have attached both images in case you want to try them on your side. It would be nice to know if it's a problem from my side only. ☹️
Many thanks again
Edit: I also installed the Offficial SL Viewer yesterday to try if it was a problem with my Firestorm, but the problem persisted.
Edit 2: I add a third picture showing that when viewing the 55% image in my inventory, it looks ok, it's opacity as normally expected. But when the texture is applied, it just looks solid.