I tested this on a couple of different versions including 10.19.9 I think something is wrong with saving form fields in general, changing the sort order of fields and then save/close does not save the changes. Also saving the details of a form field (like changing the description) of a field is not persisted
Can be seen on https://jus.dw10demo.dynamicweb.cloud/
Nothing in the logs as far as I can see
