how do i advance in hard quest for that panel mission for yshtola?

I hope I'm mistaken that you're not talking about shard quests, when you go to story there's a button for world quests, you can do 10 per day for shards for any non limited unit

It may also be referring to a mission that you already completed before you unlocked the page, which you just need to do again

If neither of those, maybe its bugged so send a ticket

You may be able to tap the tile and there may be a challenge button