I can't access the portal back after getting Cosmog?

Question

So I went through the portal and got Cosmog but forgot to go back. Ended up trading away all three,but I got Solgaleo,Lunala and Necrozma now. I walked up with Dawn Mane and then Dawn Wings in my party and nothing happened still. I'm in Lake of the Sunne,and I'm playing Ultra Moon and I hope this hasn't been asked already but I'm so confused. I walked in with Solgaleo and Lunala seperately in my party,and even had Necrozma and Solgaleo/Lunala seperate in my party. I asked my friend for help and even they're confused. I feel like I'm missing something cause I feel stupid. I did it at both day and night.

Comments

Lake of the Sunne? I think you're supposed to go to the altar after the seventh trial

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ah,I'm just stupid~

Answer 1

First off, like Demon Hunter said, you have to go to the Altar of the Sunne/Moon depending on your game that is on Poni Island, not the Lake that is at Ula'Ula Island.

I don't believe there is a specific time you need to be at to get back to the OG dimension, but there was one to get into the Reverse World in the first place.

Hope I helped.