[Bug] [Studio] Iframe Blank on Colab Instance

[mfielding92]

Note: Please do not remove the questions. Answer beside them.

1. Did you update? pip install --upgrade unsloth unsloth_zoo - Yes, Colab Auto-loads latest update, using notebook directly from Official GitHub Repo
2. Colab or Kaggle or local / cloud - Colab
3. Number GPUs used, use nvidia-smi - 1 GPU: NVIDIA A100-SXM4-40GB
4. Which notebook? Please link! - https://colab.research.google.com/github/unslothai/unsloth/blob/main/studio/Unsloth_Studio_Colab.ipynb
5. Which Unsloth version, TRL version, transformers version, PyTorch version?

• Unsloth version: 2026.7.4
• TRL version: 0.23.1
• Transformers version: 4.57.6
• PyTorch version: 2.10.0+cu128

7. Which trainer? SFTTrainer, GRPOTrainer etc - N/A

Steps to Reproduce

1. Open Notebook
2. Select Run All
3. Wait for Unsloth Studio to load in iframe, it doesn't.

Log

2026-07-22 22:07:00 [info     ] 🦥 Starting Unsloth Studio...
2026-07-22 22:07:00 [info     ]    Loading backend...
2026-07-22 22:07:00 [info     ]    Starting server...
2026-07-22 22:07:00 [info     ] run_server startup begin api_only=False host=0.0.0.0 port=8888
🦥 Unsloth: Will patch your computer to enable 2x faster free finetuning.
{"timestamp": "2026-07-22T22:07:25.604880Z", "level": "info", "event": "Imported FastAPI app in 24907.3ms"}
{"timestamp": "2026-07-22T22:07:25.607295Z", "level": "info", "event": "Ensured Unsloth directories in 25075.3ms"}
{"timestamp": "2026-07-22T22:07:25.627687Z", "level": "info", "event": "run_server pre-uvicorn setup completed in 25095.6ms"}
INFO:     Started server process [2897]
INFO:     Waiting for application startup.
{"timestamp": "2026-07-22T22:07:25.902851Z", "level": "info", "event": "Removing unsloth compiled cache: /content/unsloth/unsloth_compiled_cache"}
Hardware detected: CUDA -- NVIDIA A100-SXM4-40GB
{"timestamp": "2026-07-22T22:07:25.904693Z", "level": "info", "event": "lifespan hardware detection completed in 1.9ms"}
{"timestamp": "2026-07-22T22:07:26.159434Z", "level": "info", "event": "lifespan pre-auth setup completed in 256.7ms"}

============================================================
DEFAULT ADMIN ACCOUNT CREATED
    username: unsloth
    password saved to: /root/.unsloth/studio/auth/.bootstrap_password
    Open the Unsloth UI to sign in and change it.
============================================================

{"timestamp": "2026-07-22T22:07:26.410136Z", "level": "info", "event": "lifespan startup completed in 507.4ms"}
INFO:     Application startup complete.
INFO:     Unsloth Studio running on http://34.173.180.194:8888/ (To stop: press Ctrl+C -- on macOS, Control+C not Command+C)
{"timestamp": "2026-07-22T22:07:26.412571Z", "level": "info", "event": "Uvicorn startup hook completed in 25880.5ms"}
{"timestamp": "2026-07-22T22:07:26.413964Z", "level": "info", "event": "run_server uvicorn ready after 25881.9ms"}
{"timestamp": "2026-07-22T22:07:26.421302Z", "level": "info", "event": "   Server started on port 8888!"}
{"timestamp": "2026-07-22T22:07:26.724883Z", "level": "info", "event": "request_completed", "method": "GET", "path": "/api/health", "status_code": 200, "process_time_ms": 301.76}
{"timestamp": "2026-07-22T22:07:27.538415Z", "level": "info", "event": "\ud83c\udf10 Unsloth Studio URL: https://8888-gpu-a100-s-kkb-usc1f0-9hzedjcxrlu8-f.us-central1-0.prod.colab.dev/"}

[IFRAME WAS SUPPOSED TO BE HERE. SEE SCREENSHOT.]

{"timestamp": "2026-07-22T22:07:29.372008Z", "level": "info", "event": "Loaded default model defaults from /content/unsloth/studio/backend/assets/configs/model_defaults/default.yaml"}
modules.json: 100%
 349/349 [00:00<00:00, 48.3kB/s]
config_sentence_transformers.json: 100%
 124/124 [00:00<00:00, 15.4kB/s]
README.md: 
 94.8k/? [00:00<00:00, 10.4MB/s]
sentence_bert_config.json: 100%
 52.0/52.0 [00:00<00:00, 7.61kB/s]
config.json: 100%
 743/743 [00:00<00:00, 105kB/s]
model.safetensors: 100%
 133M/133M [00:00<00:00, 173MB/s]
tokenizer_config.json: 100%
 366/366 [00:00<00:00, 50.1kB/s]
vocab.txt: 
 232k/? [00:00<00:00, 19.9MB/s]
tokenizer.json: 
 711k/? [00:00<00:00, 54.3MB/s]
special_tokens_map.json: 100%
 125/125 [00:00<00:00, 16.7kB/s]
config.json: 100%
 190/190 [00:00<00:00, 22.3kB/s]

[LET NOTEBOOK SIT FOR APPROX 12 MIN BEFORE STOPPING IT]

=={"timestamp": "2026-07-22T22:19:19.386384Z", "level": "info", "event": "\nUnsloth Studio keepalive stopped."}

I could not find a previous bug report of this, but if I am mistaken, please let me know! Thank you.