Phil Hayton coped brilliantly with his presenting stints on BBC World and News 24 on Saturday afternoons. This was because he was the sole presenter during those broadcasts. As soon as he gave up his World shifts in favour of News 24 weekday mornings, he became rather stilted and stuffy. You're right, he just didn't do well with a co-presenter unfortunately.
Yet he worked on the Six and Nine O'clock news he could do co-presenting.
Very different kettle of fish. The Six and Nine were more dual-presentation than co-presentation. Most links were single-headed, and the double-headed stuff was close to entirely scripted (and really just for the set-piece elements of the show). There's a world of difference between that and double-headed presentation of totally unscripted breaking news, where you really have to work as a team, and support each other.
Unlike many of the 90s One/Six/Nine era presenters, Philip worked very well in the breaking news scenarios of BBC World and BBC News 24 when he was single-heading, and he could definitely cope well with the demands of that very different role. From memory, both Andrew Harvey and Chris Lowe also made the transition well - and were great on News 24.
He seemed to work well alongside Anna Jones before Kate Silverton came in, who, IIIRC, was only brought in because Anna had left for Sky. He said in an interview that he and Jones, and Joanna Gosling before that, got along famously.
Oh, sir, can we take a break for a while? It appears my intelligence circuits have melted.