We're sorry you've encountered this error. Unfortunately though, this one lies with Google Sheets itself, so it is outside of LiveFlow's control to fix it right now.
We are in active dialogue with their team on a high-priority support ticket, so we hope to see a fix soon.
In the meantime, here are some ideas for how to resolve the issue:
Refresh the page - full refresh from of the browser tab
Copy the formula from the cell, delete the cell, then paste the formula back in
Open the LiveFlow extension as though you are going to create a new report
From the Extensions menu, select Apps Script, which will open a new tab
From the code editor, make some change (add a space), then and click save
Failing all of the above, come back in a few minutes and try again
We're working on new approaches to handle large numbers of transactions, where we won't depend on these custom functions. We'll share an update when that solution is ready.