Checkbox Value is Not Saved

Hello Team,

When I tried to mark my completion of Week 1 Day 5 and Week 1 Day 6 in 2 Month Study Plan, the checkbox value is filled. However, when I refreshed my screen, the checkbox value is disappeared. Thereby, my progress is not saved.

Also, I noticed that the Colour of Checkbox is changed from “GREEN” to “BLACK”.

Can someone help me here ?

Attaching Screenshot for your reference