Hi everyone, I've been stuck on this for days and have exhausted every fix I could find. Hoping someone here can spot what I'm missing.
Setup:
- Blender 5.2.0, Render Engine: Cycles, GPU Compute
- Liquid simulation (Mantaflow/FLIP) of coffee pouring into a mug from an espresso machine
- Two separate Domains (one per cup), each set to Domain Type: Liquid, Time Scale: 1.0
- Material on the Domain: Attribute node (name: "density") → Alpha output → Density input of a Volume Absorption node → Volume output → Material Output's Volume socket
The problem:
The fluid simulation bakes successfully — I've confirmed the cache folder has complete fluid_data_XXXX.vdb and fluid_mesh_XXXX.bobj.gz files for every frame. In Wireframe view mode, I can clearly see the fluid mesh geometry inside the cup at frame 76. In Viewport Shading: Rendered mode, the liquid also displays correctly with proper color/volume.
However, when I press F12 to do the actual render, the liquid is completely absent — the cup is empty, even though steam (a separate volume shader) renders fine in the same frame.
What I've already tried (all with no change):
- Confirmed Ray Visibility > Camera is enabled (✓) on both Domain objects
- Confirmed Ray Visibility > Camera is correctly disabled (✗) on the Flow (Plane) source objects only
- Free Data + full re-Bake (Data + Mesh) multiple times
- Switched Cache Type between Replay and Modular (both tested independently, no difference)
- Disabled Simplify entirely
- Rebuilt the material node tree from scratch (Attribute → Volume Absorption → Material Output)
- Tested Principled Volume as an alternative to Volume Absorption
- Isolated test: hid every other object in the scene except the Domain + cup — liquid still doesn't appear in F12 render
- Purged unused data-blocks
- Verified there's only one relevant Domain active in the current scene/view layer
Steam (a separate Domain with Smoke/Fire, Type: Gas) using a similar Principled Volume setup renders perfectly fine in the same scene/frame — so it seems specific to the Liquid domain type or its FLIP mesh output.
Has anyone run into liquid domains rendering fine in the viewport but vanishing specifically in Cycles' final render? Any Cycles-specific volume settings I might be missing (Volume Bounces, Step Rate, or something related to FLIP mesh generation not being picked up by the renderer)?
Happy to share screenshots of any panel on request. Really appreciate any pointers!
Source: r/blenderhelp · by /u/KookyEstimate1019