I canceled my wished-for item after over two hours to try for something else, and the shrub will not let me make a new one without granting someone else's again? Do we have to grant a new wish any time we change ours'? That doesn't seem right...

My wish is also gone (after midnight reset) and it was never granted, It is also saying I need to grant someone's wish :/

This is not a bug. There are 150 spaces at the shrub. If they are all full, you have to wait until a wish is granted before you can wish. Please be patient and try again!