Siril 1.2.3 not finding r_pp_images.seq even though they exist

Software Siril
1

After a long processing run covering 6 sessions and several hundred lights, along with master Bias and master Darks, Siril is aborting with

log: Script execution failed.
*** initial call to atFindTrans failed

~~~ warning:Reading sequence failed, file cannot be opened: r_pp_images.seq.
~~~ warning:Reading sequence failed, file cannot be opened: r_pp_images.seq.
~~~ warning:Reading sequence failed, file cannot be opened: r_pp_images.seq.
~~~ warning:Reading sequence failed, file cannot be opened: r_pp_images.seq.
~~~ warning:Reading sequence failed, file cannot be opened: r_pp_images.seq.
~~~ warning:Reading sequence failed, file cannot be opened: r_pp_images.seq.
~~~ warning:Reading sequence failed, file cannot be opened: r_pp_images.seq.
~~~ warning:Reading sequence failed, file cannot be opened: r_pp_images.seq.
~~~ warning:Reading sequence failed, file cannot be opened: r_pp_images.seq.

................................................................................

... Aborted ...
................................................................................

However, those files DO exist in each of the respective session folders. Any ideas what might be going on? I am running it through SirilIC. The Siril log file is located at: https://www.dropbox.com/scl/fi/5f47q6kwd015si3de8vm4/SirilLog.txt?rlkey=ds5wju57ygjd1mfuzwskxd33x&dl=0
2

I suspect I may have found the issue: the first step in SirilIC that does the cleaning and copying files does not appear to clean the RGB/Group folder, leaving all the image_group_* and rr_image_group_* files in place. When I delete those, my runs work. In my original post, I had neglected to mention that this was a 2nd run of the same batch, after deleting a few individual lights.