command-line Render fails - Arnold licensing

[spencer]

background: Rocky Linux 10, Maya 2025, MtoA 5.5.4.

I'm setting up a new renderfarm client (eventually will use Deadline to dispatch jobs to it). I can start up Maya 2025 interactively - license is OK, and can successfully see the Arnold license server in the Arnold License Manager. That activity shows up in the "adskflex.log" file on the license server host. 

I can successfully render a sample scene in Maya 2025. 
When I attempt to use the Render command on that host, from the command line, I see this in the output:

00:00:05 2285MB | authorizing with license manager: network ...
Warning: WARNING | rendering with watermarks because of failed authorization:
00:00:05 2320MB WARNING | rendering with watermarks because of failed authorization:
00:00:05 2320MB | [clm.v1] product key not found (44)
00:00:05 2320MB | environment variables:
00:00:05 2320MB | ARNOLD_LICENSE_ORDER = (not set)
00:00:05 2320MB | ARNOLD_LICENSE_MANAGER = (not set)
00:00:05 2320MB | [rlm] solidangle_LICENSE = (not set)
00:00:05 2320MB | [rlm] RLM_LICENSE = (not set)
00:00:05 2320MB | [clm] ADSKFLEX_LICENSE_FILE = @arnoldserver.cs.washington.edu
00:00:05 2320MB | [clm] LM_LICENSE_FILE = (not set)
00:00:05 2320MB |
00:00:05 2320MB ERROR | aborting render because this is a batch render and abort_on_license_fail option is enabled

The weird thing is, there aren't any watermarks on the image I generate, but there's no logfile entries for the rendering (but it's using MtoA, and not the standalone Arnold renderer, so maybe there wouldn't be?).

My question is: why can I render interactively and not render from the command line, on the same host and with the same Maya file?

This rendering attempt does not show up in the adskflex.log file on the license server host. Yes, I can ping the license server host from the renderfarm client host.