I think your water filter has older firmware version. Try to update it by connecting MI Home app, it may resolve your issue. Older version firmware is designed to start filling water when it below 50% water level
1, Restart Problem==Check Adapter 2, Motor Working But drainage water not coming out == check ppc filter 3, water not filling in the water tank/ half filling == change water level sensor check below link for water level sensor repair 2024 ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-w1et1DdEWCk.html