[6.9.2] BTRFS raid0 pool not showing full capacity

I started with a BTRFS pool of 2x 18TB in raid0, this has been running for a few months.

I added another 2x 18TB to the pool a few days ago, this operation completed this afternoon.

Now that it has finished, I note that it does not show the expected capacity (72TB):

Data, RAID0: total=31.88TiB, used=31.87TiB
System, RAID1: total=32.00MiB, used=2.20MiB
Metadata, RAID1: total=33.00GiB, used=32.57GiB
GlobalReserve, single: total=512.00MiB, used=0.00B

No balance found on '/mnt/chiapool'

Normally I would run balance a second time before posting, but this looks like it will take another few days... I don't want to waste time and energy if this is a known bug with a possible work around.

Tagging @JorgeB because you seem to be across these BTRFS issues.

Thanks in advance