I won't post the usual form of information because this behaviour has nothing to do with my system (PS4).

The FATE Glutenous Gertrude in Lower La Noscea can be chosen to be the 10 seal worth daily mark for hunt. When it spawns, you see the mob is marked. All good till here. But this FATE is at the moment also used for the Lightning Event. There are in fact 2 versions of the FATE, one time for the Lightning Event, and the regular version. Problem is, although even in the Lightning event, the FATE mob is marked as a Hunt goal, you do not get credits for it and your log remains uncompleted after the FATE was defeated.

You basically would have to wait till the "not Lightning event"-version of the FATE spawns which is kinda ridiculous.

SE, please check your code because this might be a general problem of FATES that spawn for more than one purpouse. Best case would be that the FATE gives the event reward AND the hunt reward and if that's for whatever reason not possible, please at least stop marking the mob when it doesn't reward you as hunt mark because it is an Event mob at the moment.