Synchronizations were hard works

Didn’t use the nodes for more than a weeks.
Today start wm/grin, stuck at 2/7:99%.
So I start grin++. It Sync ¼ succeed. But it reSyn tx states from 0%, after about a hour, it reach to 99% and enter step 3/7. A few seconds later return to 2/7 with 0%.

Griners, have any suggestion.
Do I have to delete all the data everytime?