Which version of stat do you have? I get the same blank result locally on ext4 and btrfs filesystems (not over nfs) using stat 8.30 on an rpi4 (raspbian, 5.10.103-v8+).
Seems to work fine with stat 8.32 on xfs on a spot instance I have, running Rocky 9 (5.14.0-362.13.1.el9_3.x86_64).
I thought there might be more info in the changelog: info coreutils aqstat invocationaq but I’m not seeing it.