Anomaly in my trained models

[kirys]

Hi all I'm trying to create checkpoints for the Italian language using MLS as a dataset.
I've noticed a strange anomaly, my models seems unable to say short sentences, while they works well with long ones (longer than 5 or 6 words).

The models are here -> https://huggingface.co/kirys79/piper_italiano

Do you have an hint on the possible cause, and how to fix it?
Thank you
K.