There are medals that I know I’ve earned, but are showing as zero/unearned on the medals page here on halowaypoint.com:
https://www.halowaypoint.com/en-us/games/halo-5-guardians/xbox-one/service-records/medals/players/olanmills
So some of the medals I know I’ve earned but are not recorded on the page are Rocket Kills, Sniper Kills (non-headshot), Rail Gun Kills. Some of these medals, like Sniper Kill, I think, I have definitely seen pop up in-game. However, there are other medals, that I know I’ve done the action, like get a Rail Gun kill, but I don’t remember seeing the medal either in-game or on halowaypoint.com.
Also, and this is a separate problem that I’ve noticed just recently within the past hour, when trying to load my Halo 5 Service Record page on this website, I frequently get the ‘Problem Detected’ error page.