And not because it’s complex (rolling eyes), but because it makes no sense!
The texture looks like this in the Material tab preview:
This is the way it shows in the 3D view window with the Rendered rendering mode. Which does match an actual render.
BUT like this in the 3D view window with the Material rendering mode.
Sure is not as bad as the mask not working for the actual rendering, but still puzzles me why it shows like this with the Material rendering mode. Especially when another mesh (another strawberry) with basically same textures does show the transparencey correctly, both in the 3d window and when rendered.
Transparency in the Cycles view mode apparently just does not work on some GPU setups (or at all). At least I’ve never been able to get it to work.
The only real way to get it to work is to make sure you have a transparent node mixed with a diffuse node and have the view mode set to material, but the Cycles material view tends to be limited.
You can get alpha drawn in Material view mode but this is not obvious maneuver you have to take.
Switch away from Cycles to Game render, open Materials tab and in Game Settings choose Alpha Clip from dropdown Alpha Blend.
LOL!