Just released iOS 17.4 beta 3 and they say:
Messages Resolved Issues Fixed: Stickers (Memoji and 3rd party) might appear blank. (120994483)
But it didn't work for me ((
old stickers not showing up in stickers, new keep on disappearing
iPhone 15 stickers bug
17.5.1 still no stickers on iPhone 15 pro max. Worked in January (unfortunately don't remember which 17.x.x it was)