If my opponent control a face-up "Lose 1 Turn" and I Xyz Summon "Stellarknight Delteros" in Attack position, is changed to defense position by "Lose 1 Turn" effect or not?

Yes and welcome back Freddx.

By my logic, the "Your opponent cannot activate cards or effects when you special summon a monster" effect from Delteros would prevent Lose A Turn to change it into defense position, if Lose A Turn's first effect (which is not affected by Delteros' protection since it is continuous) wouldn't have already negated Delteros' effects. So yes, Bee Ba is correct, Delteros would be changed to defense position. I think.

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Thanks for the answers, so must be fixed in the YGOPro, a friend sent me this replay where Delteros remain in ATK position.

Where have you been Freddx? Did you retire, and send us your talented apprentice, EerieCode?

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Where have you been Freddx? Did you retire, and send us your talented apprentice, EerieCode?

The reason is the University, I'm kind busy for that.

I'm glad that somebody continue creating unofficial updates here, EerieCode make a really good job, I know that a lot of players want test the cards in the same day that were announced, I hope that Percy increase the speed of the updates at least with cards created by others players/programmers.

He's no apprentice. He's a very good scripter as is Freddx. I do hope that after the next update, Percy will use his updates for future cards. Maybe in your spare time when you're free, you can fix the God cards? (I'm being optimistic :P)