CoPilot SendGrid Error: TypeError: Cannot read property 'forEach' of undefined at eval [Solved]

Seem to have found a response from @copilot here Sendgrid Plugin by Copilot - #16 by melon

Although the substitution tags are formatted the right way, there seems to be some data that is not being sent when I viewed the logs. But I wonder though… it would’ve made sense if the data has not yet been created since I could simply put the actions in custom event to enable the sendgrid action to wait and be able to reference to the data. However, the data has already been created in the first place…

Off the top of my head, this could be the possible reason:
The search for the data field might be too complex and the search was not able to finish