App scaling issue for Windows Phone 8.1 Silverlight apps on Insider Build 10586 (Lumia 1520)

[Techno-Freak]

Hi,

Does anyone else have app scaling issue for some Windows Phone 8.1 apps on Windows 10 Mobile 10586, where there is black bar in the bottom on 1080 X 1920 screens?
I have upgraded to Build 10586 from Windows Phone 8.1 and only a few apps (probably built in Silverlight for WP8.1) have this issue. Looks like these are not detecting proper resolution of the device.
The Bing wallpaper download page in Insider Pro app now shows resolution of only 768 X 1280, which used to be 1080 X 1920 in WP8.1.

Other apps like WhatsApp, Twitter, Facebook Messenger also have this issue.

I've changed DPI settings in Display, but nothing helps.
Wanted to know if this is a known issue, should I go for hard reset or it won't help (might be some issue while updating, but other things work ok)?
I don't have this issue on Lumia 1320, which has lower resolution.

Screenshot on 1520:
WhatsApp

 

[Ma Rio]

Try reinstalling the apps. I don't have that black bar neither on twitter, facebook, whatsapp or any other app I use.

 

[Techno-Freak]

Tried that, doesn't help. Looks like a bigger problem, I'd do a hard reset most probably.