My custom fail2ban jail fails to load even though fail2ban-regex suggests that it should work?

I've written a custom jail and filter in fail2ban for logging into my service. The log file is located in /var/log/motion/motion.log and a failed login generates a line like this:

[0:ml1] [ALR] [STR] [Nov 02 11:42:59] handle_basic_auth: motion-stream - failed auth attempt from <ip>

My jail in /etc/fail2ban/jail.local looks like this:

[motion-auth]

enabled = true
port     = 8008
filter = motion-auth.conf
logpath  = /var/log/motion/motion.log
banaction = %(banaction_allports)s
maxretry = 3
findtime = 10800
bantime = 259200

And my filter in /etc/fail2ban/filter.d named motion-auth.conf looks like this:

[Definition]
failregex = \[0:ml1\] \[ALR\] \[STR\] \[.*\] handle_basic_auth: motion-stream - failed auth attempt from <HOST>

When i run fail2ban-regex /var/log/motion/motion.log /etc/fail2ban/filter.d/motion-auth.conf I get a confirmation that my filter does infact function as intented:

Running tests
=============

Use   failregex filter file : motion-auth, basedir: /etc/fail2ban
Use         log file : /var/log/motion/motion.log
Use         encoding : UTF-8


Results
=======

Failregex: 186 total
|-  #) [# of hits] regular expression
|   1) [186] \[0:ml1\] \[ALR\] \[STR\] \[.*\] handle_basic_auth: motion-stream - failed auth attempt from <HOST>
`-

Ignoreregex: 0 total

Date template hits:
|- [# of hits] date format
|  [2640] (?:DAY )?MON Day %k:Minute:Second(?:\.Microseconds)?(?: ExYear)?
`-

Lines: 2929 lines, 0 ignored, 186 matched, 2743 missed
[processed in 1.06 sec]

But when I try to reload / restart fail2ban to add my new filter I get a message like this:

Found no accessible config files for 'filter.d/motion-auth.conf' under /etc/fail2ban
 Unable to read the filter 'motion-auth.conf'
 Errors in jail 'motion-auth'. Skipping...
OK

Does anyone know what I'm doing wrong?

[motion-auth]

enabled = true
port     = 8008
filter = motion-auth
...