Dependable reference to a MovieFileOut me.fileSuffix digit

For reasons, I would like to see the true path of a moviefileout when set to Unique Suffix. Referencing op(‘moviefileout1’).fileSuffix supplies the digit, but it doesn’t update reliably when that changes. Without getting into janky forcecooking, is there a way to make that reference dependable? thanks

edit: Windows, latest stable build (27390)