The same loading and editing issue was resolved when I restarted my Mac - leaving me able to enjoy the illegible UI and its appalling bland appearance. Pity that such a once-great product has degenerated so much.
Same issue, all notes had disappeared, and took minutes each to load every time I needed to see them. . 6.0.3 is a horrendous buggy mess, but I can at least see my data (just(). Actively seeking an alternative - preferably in green