Automation to save MPEG failing

AFNI version info (afni -ver):
Precompiled binary linux_centos_7_64: Jul 28 2021 (Version AFNI_21.2.04 'Nerva')

Some users on a system I administer are having issues with trying to automate AFNI to get it to save out an MPEG file of a simple sagittal view of the brain through the slices.

Here is what they are doing:

afni -niml -yesplugouts t1spgr_208sl.nii  &
sleep 5s
plugout_drive -com "SET_XHAIRS OFF" -com "SAVE_MPEG sagittalimage movie" -com "QUITT"

Initially we were getting issues with missing dependencies, but I've resolved those. Now the error is:

PO: plugout connection from host 127.0.0.1 (tcp:*:7955)
PO: plugout connection name is plugout_drive
++ Starting to save images to temp files

Fatal Signal 11 (SIGSEGV) received
      ISQ_save_anim
     drive_MCW_imseq
    AFNI_drive_save_allimages
   AFNI_driver
  AFNI:main
 Bottom of Debug Stack
** AFNI version = AFNI_21.2.04  Compile date = Jul 28 2021
** [[Precompiled binary linux_centos_7_64: Jul 28 2021]]
** Program Death **
** If you report this crash to the AFNI message board,
** please copy the error messages EXACTLY, and give
** the command line you used to run the program, and
** any other information needed to repeat the problem.
** You may later be asked to upload data to help debug.
** Crash log is appended to file /home/mangstad/.afni.crashlog
** AFNI data channel aborted!

And the contents of ~/.afni.crashlog after that is:

*********------ CRASH LOG ------------------------------***********
Fatal Signal 11 (SIGSEGV) received
.......... recent internal history .........................................
-------ISQ_getoverlay [7]: EXIT} (file=imseq.c line=12262) to ISQ_save_anim {10502 ms}
+++++++AFNI_process_environ [7]: {ENTRY (file=afni_environ.c line=155) from ISQ_save_anim {10502 ms}
++++++++AFNI_suck_file [8]: {ENTRY (file=afni_environ.c line=64) from AFNI_process_environ {10502 ms}
--------AFNI_suck_file [8]: EXIT} (file=afni_environ.c line=73) to AFNI_process_environ {10502 ms}
-------AFNI_process_environ [7]: EXIT} (file=afni_environ.c line=175) to ISQ_save_anim {10502 ms}
+++++++ISQ_short_to_rgb [7]: {ENTRY (file=imseq.c line=2915) from ISQ_save_anim {10502 ms}
++++++++mri_new_7D_generic [8]: {ENTRY (file=mri_new.c line=48) from ISQ_short_to_rgb {10502 ms}
--------mri_new_7D_generic [8]: EXIT} (file=mri_new.c line=143) to ISQ_short_to_rgb {10502 ms}
-------ISQ_short_to_rgb [7]: EXIT} (file=imseq.c line=2948) to ISQ_save_anim {10502 ms}
+++++++mri_free [7]: {ENTRY (file=mri_free.c line=49) from ISQ_save_anim {10502 ms}
       mri_free -- call killpurge {10502 ms}
++++++++mri_killpurge [8]: {ENTRY (file=mri_purger.c line=259) from mri_free {10502 ms}
        mri_killpurge -- check if im==NULL ptr=0x2984bb0
        mri_killpurge -- can't killpurge NULL fname! {10502 ms}
--------mri_killpurge [8]: EXIT} (file=mri_purger.c line=270) to mri_free {10502 ms}
       mri_free -- free ptr {10502 ms}
       mri_free -- free im {10502 ms}
-------mri_free [7]: EXIT} (file=mri_free.c line=69) to ISQ_save_anim {10502 ms}
+++++++ISQ_getmemplot [7]: {ENTRY (file=imseq.c line=12133) from ISQ_save_anim {10502 ms}
++++++++AFNI_brick_to_mri [8]: {ENTRY (file=afni.c line=3995) from ISQ_getmemplot {10502 ms}
--------AFNI_brick_to_mri [8]: EXIT} (file=afni.c line=4142) to ISQ_getmemplot {10502 ms}
-------ISQ_getmemplot [7]: EXIT} (file=imseq.c line=12242) to ISQ_save_anim {10502 ms}
+++++++mri_free [7]: {ENTRY (file=mri_free.c line=49) from ISQ_save_anim {10511 ms}
       mri_free -- call killpurge {10511 ms}
++++++++mri_killpurge [8]: {ENTRY (file=mri_purger.c line=259) from mri_free {10511 ms}
        mri_killpurge -- check if im==NULL ptr=0x2985b00
        mri_killpurge -- can't killpurge NULL fname! {10511 ms}
--------mri_killpurge [8]: EXIT} (file=mri_purger.c line=270) to mri_free {10511 ms}
       mri_free -- free ptr {10511 ms}
       mri_free -- free im {10511 ms}
-------mri_free [7]: EXIT} (file=mri_free.c line=69) to ISQ_save_anim {10511 ms}
............................................................................
      ISQ_save_anim
     drive_MCW_imseq
    AFNI_drive_save_allimages
   AFNI_driver
  AFNI:main
** AFNI compile date = Jul 28 2021
** [[Precompiled binary linux_centos_7_64: Jul 28 2021]]
** Program Crash **

This does save out ppm images of each slice into the directory I'm in, but seems to be failing in combining them into a movie.

However, if I run just the first part to bring up the T1 image, then on the sagittal window I press the DISP button then select Save Anim MPG then click DONE, then click Save:mpeg and enter a filename and click SET it correctly saves out a short MPEG that goes through the slices. So the save to video function seems to be working, but somehow failing when trying to automate it.