On Quest 3, when camera background is set to transparent, transparent material objects are invisible wherever there's no opaque object behind them

Meta XR packages v78, urp 17.2, unity 6000.2.6f2, open xr 1.15.1

We are building on Meta Quest 3. We set the camera background to solid color > black+transparent, which is a prerequisite for passthrough to work. Whether we enable passthrough or not makes no difference. We have an object with a partially transparent texture, which is partially over an opaque object and the rest of it has nothing behind it. The part of the transparent object over the opaque object looks great, reflections and all, but the part of the object with nothing behind it looks totally invisible, except from the opaque parts of the texture.

It looks fine in the editor and it looks fine if we just build for an android device - it’s on the Quest 3 that this breaks. We tried switching shaders, order queue, using “additive” instead of just “alpha”, different depth write modes, plus a workaround that we found here, using the line " Blend SrcAlpha OneMinusSrcAlpha, SrcAlpha DstAlpha" in the shader but none of these made any difference.

Just a quick update… It seems that the problem occurs only when alpha on the material is zero. If I add a 1% barely visible opacity layer in my texture, the object is rendered as expected. If I have a material without a texture though, 1% of alpha affects reflections/specular too so it’s barely visible at all.

This seems like it could be the same issue as this: