ttkbootstrap: ScrolledFrame doesn’t seem to work as aspected

To test the ScrolledFrame widget i’ve wrote the follow code:

from ttkbootstrap import *
from ttkbootstrap.scrolled import ScrolledFrame


class MainView(Window):
    def __init__(self):
        super(MainView, self).__init__()

        sf = ScrolledFrame(self)
        for i in range(20):
            Label(sf, text=f"Label {i}").pack()
        sf.pack(fill=BOTH, expand=True)


if __name__ == "__main__":
    app = MainView()
    app.mainloop()

and this was the output: as you can see the Scrollbar wasn’t showing the right proportion.

I used

• ttkbootstrap 1.5.1
• Python 3.8.3
• Windows 10