uploader interface - wrong month in timestamp

[travelsbypiano]

When uploading recordings (synthesized/midi) with the drag-and-drop interface, I noticed the (YYYY/M/D) timestamp doesn't show the current month but the previous one (!)

However right after the upload is completed and signed, when it goes back to the work page - before any admin had the time to review anything - it shows the correct month.

For example, if I upload today, 5th October 2018, it shows (2018/9/5) (wrong) while uploading but (2018/10/5) (correct) on the work page after the upload.