"My alliance found a trick for this that will work. I did this trick and I won 4 completion grants in a row! Okay here is how it goes first off go to play fortunas, find the item you want (refresh the game if the item your looking for isn't there) whenever u find that item you want, wait till the flash hits it (for better luck wait until the item has been flashed twice) start counting when flash lands on it. As soon as you count to 10, click the "choose" button and you will get the item u desired. At first it will take a couple tries (took me 2 weeks of fortuna to master it) but overtime getting it will be really easy. Hope this helps and good luck!
This was not my post, IDK who it was from... but other people said it helped them so maybe it works.