Hello!
Thank you for making a bug report!
It is helpful to have a replay for these types of scenarios as Blue-eyes Abyss Dragon has a lot of requirements. One of these being that a “Blue-eyes White Dragon” must be on the field or in the graveyard to activate the effect at the point of the Abyss Dragon being summoned to add the ritual card or polymerization, or at the end phase in order to add the monster.
If this requirement isn’t meet, you will not be allowed to activate Blue-eyes Abyss Dragon.
If you have a replay this would be greatly helpful to share so that we can check the exact scenario. But in the case that a replay isn’t available, I’ll close this bug report in a few days.
Thank you for helping make Omega be the best that it can be.