Same saddle (Charge spoon) and shorts combo that i’ve done hundreds/thousands of miles on (inc a few century rides) with no problem and on a few different bikes (road and mtb) – but put on a new bike and 32mile ride last night and saddle sores.
What’s to blame? Slight different position as different frame/bike meaning chaffing in different place? That would make sense if i only ever ran that saddle/shorts on one bike, but all bikes have the same saddle.
I’ve had similar problems this year, never been an issue to me previously, multiple bikes and saddles but this year i seem very susceptible to them. In you case checking the bike fit is the same across all bikes is a good place to start, but with anything each saddle won’t be exactly the same, worth sanity checking the rails aren’t bent etc