After change my phone I've tried to sync my Flight history with phone
On my old phone I enabled upload checkbox and it quite long uploaded more than 50 records
On new phone I do sync with cloud and also it was done with success.
However flight history is Empty.

DJI Mavic 2 Pro
DJI Go4

Wasnt there an optoin in the go4 setting for how long to sync for,  you may need to select all flight logs.

Via USB, I'd just download the flight logs from the old phone to computer and the upload copies to the new phone.