Just want to mention how to solve a problem I had after upgrading from J2.5 to J3.x (Chronoforms V4 on both installations and followed migration instructions).
Using the form Wizard after migration to J3.x, some forms did and some forms did not save changes I made in the form.
I found that the forms that did save, had the option Form Wizard Mode (General tab) set to 'Easy' instead of 'Advanced (default)'. I remembered that I used 'Advanced mode' in J2.5. Once I changed the mode to 'Advanced (default)' again, the forms saved properly in Wizard mode.
My theory (best guess) is that this option was set to 'Easy' during migration from J2.5 to 3.x. I have no proof of that though.
Anyway, if you encounter similar behavior, this post might help you to solve it for this particular case.