Well…I solved the issue. It was due to Orchid. Either the recent update to Revit 2024 or updating to the newest version of Orchid was the issue (I did both of those things around the time that this may have broken). In either case, removing the Orchid package fixed the issue.
To be clear, no Orchid nodes were used in the graph…simply having it installed was causing the issue. This may be due to a strange interaction between Orchid and Orkestra that is currently being looked at. I am copying @Mostafa_El_Ayoubi @erfajo into this for their information.
It was the following post that led me to test this: Issue Exporting to Excel since upgrade to 2024 - #16 by nathan.dent
Thank you for all of your help! I will take your Concatenate String idea and use that in some other situations moving forward.