Board Thread:Questions and Answers/@comment-36743418-20180828112057/@comment-34713116-20180828113524

Have you checked your inventory to make sure you hourglasses or you looking at the part of the screen where it says :

Reverse

(blurb)

Available: 71 (select)

If it's the latter then all that's showing you is how many units you have that can be reversed. You may not actually have any hourglasses.