Content Disappears/ Deletes itself when rearranging 'Bullets' / Blocks

I’ve come over from ROAM but still a tech newb. On more than one occasion multiple blocks of info have disappeared (been deleted?) when I try rearranging ‘Bullets’ (‘blocks’ ) via dragging them up or down. I’ve looked to see if they got nested elsewhere but they seem to be deleted entirely. TWO QUESTIONS: 1 - Can I recover the deleted info (and how) and # 2 - How avoid this from happening? TIA