netatalk 'vol size limit' causes Time Machine to report 0 KB available

When I set the vol size limit in /etc/netatalk/afp.conf, Time Machine initially reports the correct amount of available, but fails on backup and reports that 0 KB are available. I am wondering if this might be because I have a share pointing to /data and another (Time Machine) share pointing to /data/mbp_time_machine. The [netatalk docs](https://netatalk.sourceforge.io/3.0/htmldocs/afp.conf.5.html) specify that "you MUST NOT use this volume to store other content when using this option", but I do not know if they are referring to the AFP volume or the actual logical volume on the host. Below is my afp.conf:

;
; Netatalk 3.x configuration file
;

[Global]
; Global server settings
hostname=redacted_afp
[Homes]
basedir regex = /home

[redacted_afp]
path = /data

[carson Time Machine]
path = /data/mbp_time_machine
time machine = yes
vol size limit=1000