Why am I not allowed to change a custom body or sublist field value on an invoice that is grouped, getting this error: FIELDS_1_CANNOT_BE_CHANGED_AFTER_INVOICE_IS_GROUPED

AI generated answer (using internal Slack threads):

The error message

FIELDS_1_CANNOT_BE_CHANGED_AFTER_INVOICE_IS_GROUPED

is a system restriction in NetSuite when dealing with grouped invoices. Once an invoice is grouped, certain fields become locked and cannot be changed. This is to maintain the integrity of the grouped invoice and prevent any discrepancies that could arise from changing the data after the invoice has been grouped. In your case, you are trying to change a custom body or sublist field value on a grouped invoice, which is not allowed by the system. This is why you are receiving the error message. The only way to change these fields would be to ungroup the invoice, make the necessary changes, and then regroup the invoice. However, this could potentially cause other issues and is generally not recommended. Please note that this is a system limitation and not something that can be bypassed with scripting or other workarounds. ****** Disclaimer: This response was generated by an artificial intelligence assistant based on previous conversations from multiple Slack channels, and may contain inaccuracies or mistakes. ******