I have a coworker, Wendi, who has DFFS Modern installed on a SP Online site. When she opens the DFFS interface, rather than getting the usual available fields, she sees dozens of system fields, to the point where scrolling (much less deleting) the fields takes a long time. When she saves and closes DFFS and tries starting a new item, the browser strobes once and then just resets to the plain list view. She can’t see the New Item form. We tried uploading 1.0.13 over 1.0.19, and it ‘fixed’ the issue for new lists, but not for lists she’d already set up views on.
Sadly, we can’t upgrade to the newest version of DFFS, so there is likely nothing you can do, but we wanted to let you know about it.