Check you don't have a solo on an unused track or that the Master is muted or a plugin in the Master bus is stopping flow. I can replicate the same result by exporting with the Master bus muted.
Macmini 8,1 | OS X 13.6.3 | 3 GHz i5 32G | Scarlett 18i20 | Mixbus 10 | PT_2024.3.1 ..... Macmini 9,1 | OS X 14.4.1 | M1 2020 | Mixbus 10 | Resolve 18.6.5