An error in version 8 has been found which creates what looks like blank rows in the property list screen. Real properties are hidden by these blank lines. This issue will not affect all people. It will only affect people who have got properties set up as 'units'.
No data has been lost, it just can be seen. However you could still access these properties by going to the owner details screen and clicking the properties tab.
This issue has been fixed. The new version is version 8.02 and can be downloaded now. Sorry for the inconvenience.