Big Picture Mode shows expiration date of trading cards in the Unix time instead of readable form

[xplt]

Your system information

• Steam client version: Built: Dec 20 2016, at 02:18:40 / Steam API: v017 / Steam package versions: 1482214037
• Distribution (e.g. Ubuntu): Ubuntu 16.10 (64 bit)
• Opted into Steam client beta?: Yes
• Have you checked for system updates?: Yes

Please describe your issue in as much detail as possible:

If a trading card (I presume, it's true to any limited time usage item) has an expiration date then Steam will display the date in the Unix time format instead of readable form. See the screenshot:

Steps for reproducing this issue:

0. Earn a trading card with expiration date either by voting in the current winter sale or by using the discovery queue
1. Start Steam in the Big Picture Mode
2. Open the Inventory: Click on your avatar in the main menu -> [Options] View Inventory -> Steam
3. Scroll up to the received trading card and click on it

[xplt]

Coupons are also affected

[thackel]

Its still an issue with the latest Beta client: