I've just tried the latest nightly build and the issue got better but it seems there are some leftovers.
The global bus signals on the first root schematic sheet (no prefix) are exported as "/D8" (for example), while the same bus signals on non-root schematic (with some sheet prefix) are exported as "D8". So for pcbnew those are different nets and they will be disconnected.
Thanks for the quick response to this.
I've just tried the latest nightly build and the issue got better but it seems there are some leftovers.
The global bus signals on the first root schematic sheet (no prefix) are exported as "/D8" (for example), while the same bus signals on non-root schematic (with some sheet prefix) are exported as "D8". So for pcbnew those are different nets and they will be disconnected.