[erlang-questions] SIGUSR1 isn't writing a crash dump?

[Roger Lipscombe]

I've got a release, using OTP-21.0, which I'm starting by using a
relx-generated script (relx 3.26.0, managed by erlang.mk).

When I send it SIGUSR1, it quits, but without writing erl_crash.dump

I'm using ERL_CRASH_DUMP to set the location to somewhere writable.
Using erlang:halt("whoops") from a remote shell successfully writes
erl_crash.dump, but SIGUSR1 doesn't. The daemon simply quits.

Searching the internets got me to OTP-13425, which was apparently
fixed in OTP-19. Did it somehow become un-fixed? Or am I missing
something else?

Cheers,
Roger.