As @jcolp has mentioned before, the issue here is a potential for a race condition and not all systems are similarly affected. I’m not aware of a specific configuration that can reliably reproduce it, nor have I ever seen it on a system I control.
FreePBX 13 didn’t have the gui option to enable, but pjsip transports had reload enabled by default until only very recently. For years this setting being enabled was under the radar and not an issue until the latest versions of Asterisk 13 were published, and users started reporting issues. In Asterisk SIP Settings ver. v13.0.131.11, transport allow reload is disabled and can’t be enabled in the gui.
It also is the case that the default setting in 14 did not appear to be an issue for quite a while, again corresponding recent versions of Asterisk. Starting in SIP Settings module versions 14.0.27.19 and 15.0.6.20, this value is disabled by default. Any new install or upgrade from 13 that gets one of the these versions will have it disabled by default. As of right now, an older version is bundled with the current ISOs, but that will be resolved at some point when new ISOs are created.
edit: latest versions of 14/15 Asterisk SIP Settings will throw a dashboard error when transport reload is enabled:
