Can anyone suggest why this errors? It's in a M/R script, the record id is correct, the field id is correct, it's a checkbox so true should be the value it expects not 'T'. Loathe to load and save the record if I can avoid it 😉 Wondering if it's just because Inbound Shipments are a bit of a "fruity" record 😉 (yes I'm aware it's commented out 😄 )

Not familiar with the (fruity) record type, but understand your concern! What kind of error are you receiving?

Have you tried doing the field id as a string in the values parameter. Documentation shows two examples second using a custom field which uses a string for the field id so {'custrecord_cat_ib_allcic':true}

Make sure the value it expects is also not 'Y' (vs. 'N').