This appears to be a bug in SL 2018 Web Apps (with the latest April HF) -

1. Log into Web Apps and start a new timecard, save.

2. Close that browser tab, but do NOT close the browser

3. Add a new browser tab and go to the WA site again.  At this point, it shouldn't prompt for login again as you have logged into before in the same browser session.  This is working as expected.

4. Open the timecard you created in step 1.

5. Instead of hours, it will now display things like 3NULL0, 0NULL0... in every cell.   See attached.

Please confirm and resolve.