Thank you for the quick response. I spent the past few minutes typing up a long response with my code, explaining how I built the custom dataset and passed it along to the trainer when I noticed a typo in my code. Turns out I was sending just the list of emails, not the encoded ones, when I called the subclassed dataset function to create my dataset. trainer.train() appears to be functioning correctly now and I will update this if I run into any further issues during this finetuning loop or with my results.