Using glonass (instead of Beidou) will give you more options in terms of ambiguity resolution, so consider using it!
I have experienced this issue with a huge amount of cycle -slips on glonass before. It is usually due to high voltage power lines (240 volts or higher, can’t say if it happens for 120 volts) beneath or next to the receiver (within a 3-4 meter radius).
It is resolved by moving the receiver away from the power line, and then all is well again.