Does anyone know of any way to get the Internal IDs of individual Transaction records in a Statement template? Neither line.id nor line.internalid works, and formula fields do not appear to work either. Is a custom Statement generation script the only option?

i don't have an example one i can find quickly but i'm pretty sure this is possible in the native statement template, just fyi. if you didn't already figure it out, i can try to find one

I haven't figured out a syntax that works quite yet

ah shoot, sorry - i found my example but realized i misread your question, i don't know if it is possible to get the internal id specifically. might have to use a custom field that sources it in or something.

use a custom field that is populated via a workflow, you can then mass update any open invoices... bit of a pain but once its done you dont have to think about it again