unfortunately, thats just how rng works in this particular game. often get trash after trash of the exact same thing over and over. happens especially when you are after a particular item and it just wont drop. also, if you are doing the same event/activity over and over, the loot tables seem to get borked this way. i guess its meant to be a disincentive to farming. which is in itself dumb because its not like theres shared loot or something. my advice would be to break up your farming sessions with different activities so it 'resets' your rng. hope this helps