I had the same issue. I added some CSS to add a temporary fix.

.nx-field .nx-richtext-input { height: auto !important; } ``` 

My field was rich text, but just substitute with the long text area class.

Sorry to be so dense, but what should I use for the long text area class?

For long text area you would use ‘.nx-field textarea’ instead of ‘.nx-richtext-input’

Thanks.  It’s odd because it’s doesn’t exactly adjust like the rich text does-it just adds an extra line for all fields but still doesn’t auto-grow past that. Is this expected for long-text fields?