I first noticed this a few weeks ago. I enter expenses through the Concur Mobile app (v 9.75.2). Daily expenses are dated appropriates. When filing expense reports, I select "Import Expenses" and select the appropriate expenses from the "Available Expenses" pane. On that pane, I can see the expense, amount and date are correct. However when I "Move to Current Report", the date of every expense moved is changed to the last date of the report. (I thought at first this was a user error on the mobile app, but last week I paid particular attention to ensure every expense was recorded correctly.)
Can you try manually creating an expense on the report using the current date? If you can't, it is most likely due to your Concur instance being in a different timezone.
Do revert with your findings on the matter.