Make sure the correct Twitch account is linked and then head to https://www.bungie.net/7/en/Codes/Partners Use the 'refresh' option and the emblems should now appear on the list, if they do then restart D2 and check collections. If they don't then contact Twitch support to see if there are any issues, if Twitch say there aren't then wait a few hours and then retry the refresh option.