[BUG] All relationship having timestamp 1899 label after import form Excel

After I exported my diagram to Excel where I just renamed column names (to uppercase) globaly, after reimport Excel back to VP I see timestamp labels on all relationships in diagram:

Sorry for the problem you met, but, I cannot repeat your problem.

If the column name is ‘modified’, it will make Excel Importer cannot import the column.
As below:

But from your description, seems you can import your changes.
May you provide more information to us for checking this problem?
Such as creating a dummy project to repeat the problem, and attach the .vpp & .xlsx here?

Dont have time now, but eventually will get to this again.