I had a difficult time with the front DR on one of the bikes, I ended up going as far as removing the DR and starting from the beginning, there is a very specific process of steps, and items you have to set, to get it right.
I will add, for someone like me that just got back into cycling recently and had not worked on bikes for awhile, the manuals are a little vague sometimes, assuming I guess that the user is more experienced (I was not).
So take your time, don't jump around, follow the steps, and check as you go.
You may have done all that, and apologies if this isn't your first rodeo

Pics or videos would help...I see you only have two posts so you may not be able to do that yet.

One more thing, if you have a brazed on mount, the R8000 front DR has a screw that is "buried" in the middle of the DR that adjusts the angle of the DR. It has to be in contact with a solid surface. Shimano provides a small curved metal piece that attaches with double sided tape to be used if the bike doesn't have a solid bearing surface, very important on CF frames, but needed for any frame that doesn't have a solid metal accommodation. Also the tape should be applied to one edge of the plate so the screw pushes the plate onto a solid part of the frame, not on the tape.