Custom Node Testing
Expected Behavior
When passing a batch of images to the Join Image with Alpha node, it should return a batch of images.
Actual Behavior
The Join Image with Alpha node always returns a single image.
Steps to Reproduce
- Run this workflow: Bug.json
- Notice that it only returns a single image.
Debug Logs
[START] Security scan
[ComfyUI-Manager] Using uv as Python module for pip operations.
Using Python 3.10.16 environment at: env
[DONE] Security scan
## ComfyUI-Manager: installing dependencies done.
** ComfyUI startup time: 2026-02-21 16:00:03.213
** Platform: Linux
** Python version: 3.10.16 | packaged by conda-forge | (main, Dec 5 2024, 14:16:10) [GCC 13.3.0]
** Python executable: /home/pauan/.config/pinokio/api/comfy.git/app/env/bin/python
** ComfyUI Path: /home/pauan/.config/pinokio/api/comfy.git/app
** ComfyUI Base Folder Path: /home/pauan/.config/pinokio/api/comfy.git/app
** User directory: /home/pauan/.config/pinokio/api/comfy.git/app/user
** ComfyUI-Manager config path: /home/pauan/.config/pinokio/api/comfy.git/app/user/default/ComfyUI-Manager/config.ini
** Log path: /home/pauan/.config/pinokio/api/comfy.git/app/user/comfyui.log
Using Python 3.10.16 environment at: env
Using Python 3.10.16 environment at: env
Prestartup times for custom nodes:
0.2 seconds: /home/pauan/.config/pinokio/api/comfy.git/app/custom_nodes/ComfyUI-Manager
WARNING: You need pytorch with cu130 or higher to use optimized CUDA operations.
Checkpoint files will always be loaded safely.
Total VRAM 15838 MB, total RAM 96175 MB
pytorch version: 2.7.0+cu128
Set vram state to: NORMAL_VRAM
Device: cuda:0 NVIDIA GeForce RTX 5070 Ti : cudaMallocAsync
Using async weight offloading with 2 streams
Enabled pinned memory 91365.0
Using pytorch attention
Python version: 3.10.16 | packaged by conda-forge | (main, Dec 5 2024, 14:16:10) [GCC 13.3.0]
ComfyUI version: 0.14.1
ComfyUI frontend version: 1.39.14
[Prompt Server] web root: /home/pauan/.config/pinokio/api/comfy.git/app/env/lib/python3.10/site-packages/comfyui_frontend_package/static
### Loading: ComfyUI-Manager (V3.37.2)
[ComfyUI-Manager] network_mode: public
### ComfyUI Version: v0.14.1-24-g7591d781 | Released on '2026-02-21'
Other
This is happening because the images are batched, but the mask is a single value.
However, this shouldn't be a problem, because every other node in ComfyUI is able to correctly combine a batch with a single value.
For example, when passing a batch of images to the ImageCompositeMasked node, it returns a batch of images, even if the source and mask are a single value.
So the behavior of Join Image with Alpha is different from every other node in ComfyUI.
In addition, the RepeatMaskBatch node doesn't exist, so there is no easy way for the user to fix the incorrect behavior of Join Image with Alpha.
Custom Node Testing
Expected Behavior
When passing a batch of images to the
Join Image with Alphanode, it should return a batch of images.Actual Behavior
The
Join Image with Alphanode always returns a single image.Steps to Reproduce
Debug Logs
Other
This is happening because the images are batched, but the mask is a single value.
However, this shouldn't be a problem, because every other node in ComfyUI is able to correctly combine a batch with a single value.
For example, when passing a batch of images to the
ImageCompositeMaskednode, it returns a batch of images, even if thesourceandmaskare a single value.So the behavior of
Join Image with Alphais different from every other node in ComfyUI.In addition, the
RepeatMaskBatchnode doesn't exist, so there is no easy way for the user to fix the incorrect behavior ofJoin Image with Alpha.