I would think that Bernardo being preferred on the bench is down to his added versatility in more positions than Montoya,.
The only mystery is why he wasnt restored to the team over Bruno as to reiterate CH said originally it was a tactical move to bring back Bruno
He was training during the week and in the galleries on the Albion website.
https://www.brightonandhovealbion.com/news/2018/october/gallery-training3/
Players that are left out of the 18 aren't automatically injured. We have a 25 man squad. Its inevitable.
Hughton likes to have 2 defensive slots on the bench. Bernardo and Balogun are more flexible in terms of both being able to play across the back than Montoya.
Bruno had a good game v West Ham.
Its not (much of ) a mystery
I think it is more likely to be. Especially in an away game. What do the opposition have in their armourment. Then who do we have available to combat that. Home games very different. It's about who we have who it best suited to open their defence up. It's absolutely brilliant we can look at players outside the 18 man squad and think "why ain't they in the squad". That's a sign that we are getting close to having a capable PL Squad instead of a PL Team.
Be interesting to know what's happening with him. From what we've seen so far he is very good whereas Bernado is not. So why is he not playing or on the bench?