@Paparazzi I believe these delivery notes you are showing never had Delivery date entered in the first place. In yesterday’s version I have changed that so all transactions must have a date (not just delivery notes but all transactions). This was to fix unrelated issue.
Manager didn’t lose any data. For transactions which didn’t have a date entered previously, the date is now set to 01/01/0001. When you edit the transaction with date 01/01/0001, Manager will auto-fill current date.
What I suggest, go through all delivery notes with date 01/01/0001 and change that to date it should have been in the first place.
I’ve noticed you have custom fields on delivery notes to capture various dates, perhaps these 66 delivery notes had Delivery Date emptied on purpose because you have Loading Date and you enter delivery date only when delivery is confirmed?