Worlds Tokens Stash Disappearing

The window with the button to claim the tokens stash for the Worlds Tokens is randomly disappearing and re-appearing in the missions menu as the days go by. I assume that the stash will last for as long as the tokens do which is until December 19 or so, correct? The problem I have with this is that I bought a good amount of RP ($50) a few days ago in hopes of getting the worlds pas. When I went to buy the worlds pass, I checked my missions menu to see how many tokens I has stashed to find it was not there. So, I thought maybe Riot had canceled the stash without warning after Worlds ended. So, I decided to skip buying the worlds pass. The next day, after I had spent my RP on miscellaneous orbs and skins, the stash re-appeared in the missions menu. I was understandably a little frustrated because I would have spent that RP on the Worlds pass if it weren't for a visual glitch (I assume that's what it is). Just wanted to let Riot know and see if anyone else is having this problem.