Adobe Audition "Unable to Open a Required File"

I am currently working on a project where my client has edited some audio for a podcast in Audition, and is trying to export it as an OMF for me so I can mix and master in Pro Tools. The first two episodes we were able to export successfully, but for the third episode, the client suddenly received an error that said "unable to open a required file" during the OMF export process. They sent the Audition session to me and I attempted to export it as an OMF after downloading Audition to see if it would work for me. I got the exact same error message on my end.

Both my client and I had the same export settings as below:

-48000 Hz Mono, 24-bit (all files are in mono)

-Media: Referenced

-Media Format: WAV

-Trim Audio Files

-Handles: 0:01.000

-The estimated OMF file size is 8.50 GB

When I attempt to export the OMF, it goes through the entire export process and makes a folder full of all the audio clips. However, when it comes time to make the actual OMF file, that is when the error pops up, and I'm left with a folder of rendered clips but no OMF. Nothing changed between the first two episodes and this one, so I'm unsure why the first two sessions successfully exported, and this third one did not.

I've seen some posts here where people had a similar issue, but it seemed like switching from encapsulated to referenced audio fixed the issue for them, where as it doesn't seem to make a difference for me. I tried messing around by selecting the "export to premiere pro option" but received the same error. However, when exporting as FCP XML Interchange format, I was able to import that into Premiere and export an OMF from there. It seemed to have almost worked as a solution, but I lost all of the client's automation work they had done in Audition. 

I am personally not very familiar with Audition, so I'm not sure if this is an easy fix, or if there is a better way to export it so I can continue editing in Pro Tools. Please let me know if there's any additional information I can provide to try and shed more light on the situation. Thank you!