Input/output error on aarch64 (raspbian on Pi 3B+)

[TudbuT]

When I try to use reptyr on my raspberry pi (installed from the debian repositories), it will always fail with an Input/output error:

869 is a fish shell:

tudbut@tud-pi-red ~ [1]> reptyr 869
[-] Timed out waiting for child stop.
Unable to attach to pid 869: Input/output error

8218 is a sleep process (same problem in foreground, background, and when stopped):

tudbut@tud-pi-red ~ [1]> reptyr 8218
Unable to attach to pid 8218: Input/output error

2560 is a cargo install process running in sshd:

tudbut@tud-pi-red ~ [1]> sudo reptyr -T 2560
Unable to attach to pid 2560: Input/output error

I can provide more information if requested.