No Validation Loss logged (possibly related to train_on_responses_only?)

[selalipop]

Evaluations are being run, but no validation loss is logged or sent to WandB

The console shows that eval is running, but displays a table along the lines of:

eval loss	validation loss
1	no log
.9	no log
.8	no log

WandB shows evidence validation run occurs, but doesn't display loss either:

from trl import SFTTrainer
from transformers import TrainingArguments, DataCollatorForSeq2Seq
from unsloth import is_bfloat16_supported
import os
os.environ["WANDB_PROJECT"] = "my_project"  # name your W&B project
os.environ["WANDB_LOG_MODEL"] = "checkpoint"  # log all model checkpoints


trainer = SFTTrainer(
    model = model,
    tokenizer = tokenizer,
    train_dataset = train_dataset,
    eval_dataset=validation_dataset,
    dataset_text_field = "text",
    max_seq_length = max_seq_length,
    data_collator = DataCollatorForSeq2Seq(tokenizer = tokenizer),
    dataset_num_proc = 2,
    packing = False, # Can make training 5x faster for short sequences.
     args = TrainingArguments(
        fp16_full_eval = True,
        per_device_eval_batch_size = 2,
        eval_accumulation_steps = 4,
        report_to = "wandb",
        run_name = "run-name-here",
        per_device_train_batch_size = 4,
        gradient_accumulation_steps = 4,
        gradient_checkpointing=True,
        warmup_steps = 5,
        do_predict=True,
        logging_first_step=True,
        num_train_epochs = 3, # Set this for 1 full training run.
        save_steps = 88,
        evaluation_strategy="steps",
        eval_steps=88,
        do_eval=True, 
        learning_rate = 1e-4,
        fp16 = not is_bfloat16_supported(),
        bf16 = is_bfloat16_supported(),
        logging_steps = 1,
        optim = "adamw_8bit",
        weight_decay = 0.01,
        lr_scheduler_type = "linear",
        seed = 3407,
        output_dir = "outputs",
    ),
)

---

from unsloth.chat_templates import train_on_responses_only
trainer = train_on_responses_only(
    trainer,
    instruction_part = "<|start_header_id|>user<|end_header_id|>\n\n",
    response_part = "<|start_header_id|>assistant<|end_header_id|>\n\n",
)


trainer.train()

Very similar settings work when using plain SFTTrainer in another project