I cleared it, but...

There's a hidden quest where you get 15000 gems after clearing Stage 60. I cleared it, but I haven't received the reward, and after waiting for about 3 days, it still wasn't verified as cleared. I even attached screenshots and contacted support, but an AI told me, 'You have not achieved the clear condition, so we cannot verify it.' I've cleared Stage 74, and Stage 60 ages ago... 15000 gems is a lot, so it's frustrating that it's not being verified. Has anyone else experienced not getting credit for clearing a stage after contacting support in other games??