Stacking rewards for Meltan Quest

When you stack encounter rewards, they are literally stacked. Only one encounter appears, and when you click on it, you'll get the Aerodactyl. Once you catch that, then you'll get the Anorith encounter.

You did nothing wrong except misunderstanding how the stack works.

Too much work, As a level 40 Research has lowest priority.

Your question seems to have been answered already, the Anorith is there, behind the Aerodactyl.

Just want to point out that the stardust in the two last stages is much more valuable than the exp. It's not even as much exp as one ultra friend gives you, but that stardust is equal to 170 normal catches. So make sure you use a star piece when you cash in the last two reward stages.

This morning found my last Omanyte that I've been waiting weeks for...go plus didn't catch it. Guess I have the Kabuto field research task though, have yet to do a raid to fulfill it.***Finished the quest, beat a tier 3 task and gave me the final omanyte. Did star piece and hatched four 7k eggs and four 5k eggs, total star piece haul was 57,000 stardust.