I have a similiar problem (also on PS4):
found and defeated all 3 champions, looted their bodies (even though with 2 they were still animated!)
got the book from the stable
constructed the standard,
But when i get to the trainer, there is no dialogue option to advance to the specialized class of champion.
the journal log has now reset to 0 out 3 Champions killed (but I have defeated them all)
Quest is bugged, so I can't advance my character.
This is such a great game, but this has prevented any further development of my character, please sort it out in the next fix!
I've had the same problem too and tried it 3 different times now. The first time, I found the book beside Blackwall and completed the rest of the quest to find the quest now said I did not have the book any longer. I tried to buy it from the book merchant and it was not there either. I returned to a previous save point before entering Skyhold and tried it all again, this time I completed all of the other quest tasks before acquiring the book from beside Blackwall, but once again once I got to the trainer it said I didn't have the book. I tried a third time today in a different order and the same thing happened. Very frustrated! Please fix this bug asap, holidays from work are running out and I don't wish to continue playing with the other specializations.
Also on PS4 with up-to-date version of the game.
Sorry to hear about your problem,but you're unlikely to get an "official response" from EA here.
The AHQ is for "player-to-player" technical self-help and game-play discussions.
We're all just fellow gamers, doin' the best we can...
I had a problem like this but on the ps3 version, I got both books first, and then defeated the cahmpions for their heraldry, and got the veridium, still the quest mark showed as if i hadn't located the book, turns out all i had to do was to go to codex and check in hystory, if there's an entry called champions of the just, that means you did read the book, if thats the case then go to the requisitions table where the quartermaster is and construct the standard, that should complete the quest, after that go report to Lord whatever his name is.
