I’m only typing this in hopes it helps you narrow down your issue. I’m using render callbacks (to a function and not a php template file). I have none of the issues you describe. I have not tried a render template at all, so I can’t comment there.
I can edit in preview mode or edit mode (I default to preview mode) and both will reflect the changes in preview mode either immediately (in preview mode) or when I swap to preview mode from edit mode.
So far I’m only using text fields, paragraph fields, and checkboxes.
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