Fine-tuned 3.5 outputs blank

Hi All – I’ve fine-tuned 3.5 to generate a particular type of script file, by showing it examples of that script format with descriptions and a context that it’s an engineer’s assistant providing detailed script files. One (abbreviated) example training sample:

{"messages": [{"role": "system", "content": "You are a mechanical engineer's assistant, providing detailed..."}, 
{"role": "user", "content": "Camera Lens Cap Holder: A (parametric) buckle..."},
{"role": "assistant", "content": "lens_diameter = 58..."}

After training, when I query with that same context, it outputs literally nothing. When I use a very different (or no) context, it does provide output.

Anybody come across this before? Not even sure how to diagnose this one. Some examples have unicode, and all have linebreaks included as \n … maybe something there?

Happy to provide more details. Thanks for the help!