This article describes how FormSlab and DoubleWall behave in IMPACT 17.2, and what changed in IMPACT 17.3 specifically regarding saving/storing of elements. 
It also describe the process for a project in 17.2 moving to 17.3 (after the migration).

IMPACT 17.2 behaviour

FormSlab

Elements are first marked then saved when generating shop drawing or as a separate save to database.

All components are added to the element when shop drawing is generated.

When changes are made on floor plan no indication is showing that the element is not saved.

DoubleWall

Elements are first marked then saved when generating shop drawing or as a separate save to database.

All components are added to the element when shop drawing is generated.

When changes are made on floor plan no indication is showing that the element is not saved.

What changed in IMPACT 17.3

FormSlab

Elements that are matching can get the same element mark if the setting is changed in Project Properties (Default is as before Never – always use new mark).

Components need to be added to the element (if not directly added when drawn) with add (just like for all other element types).

When changing an element that is saved it will be indicated with the * after the element and change in color so that missing to save after the change will be avoided. 

DoubleWall

Elements that are matching can get the same element mark if the setting is changed in Project Properties (Default is as before Never – always use new mark).

Components need to be added to the element (if not directly added when drawn) with add (just like for all other element types).

When changing an element that is saved it will be indicated with the * after the element and change in color so that missing to save after the change will be avoided.

Existing elements when moving from 17.2 to 17.3

FormSlab

The unsaved elements that only have been marked will be unmarked.

The elements that have been saved (and shop drawing generated) will get a star  after the element mark once edited.

If you have a pending update plan that one can’t be performed so instead you need to remove the element (answer no to remove from database) and then generate it in again.

DoubleWall

The unsaved elements that only have been marked will be unmarked.

The elements that have been saved (and shop drawing generated) will get a star  after the element mark once edited.

Recommendations before upgrading to IMPACT 17.3

Make sure that your floor plans are updated before migrating to 17.3.