Form Field Templates that aligned perfectly fine with the classic experience will be applied incorrectly half of the time when using the modern experience. I'm not sure if it's under workflows, or while trying to send as a default document. When the document comes up to be "previewed", sometimes the intial view for all of the pages of the document appear to be very tiny. Usually, when this happens, the form field templates are either: A) misaligned, B) not to scale, C) both A and B. Please investigate and find out why this is happening only sometimes.