First I opened HeidiSQL and opened the table "sales_order_grid" from my magento 2 database.
Then I ran a routine from my magento 2 onlineshop to add two columns to the table "sales_order_grid" .
Then I refreshed HeidiSQL with F5 and by pressing the refresh button, to see if the script worked, but the two columns were not there.
So I thought I did something wrong and wasted alot of hours of debugging until I figured out that HeidiSQL Refresh is just broken.
After I closed HeidiSQL and opened it again, it suddenly showed the new columns.