Hi Igor,
I purchased my VivoTab RT Just over 1 week ago, camera was fine & included options like Sepia, etc.
Installed Windows 8.1 Update because I kept being prompted. After several attempts it finally installed.
Today I decided to test flash in a dark room. No Flash... no option to choose it - and the effects options such as Sepia are gone.
So you are not the only one with this problem. Sounds like a worldwide issue. Programming in the 8.1 Update didn't take the VivoTab's camera & flash into consideration.
Couple days after I purchased VivoTab RT - ASUS announced they were dropping it from their line...hence no support from ASUS.
On 11/22/13 - Nokia Lumia 2520 started selling in my area. Still runs RT, but faster processor and brighter full HD screen. The Nokia camera does not have a flash. However it does have a Zeiss lens.
From the online research I've done so far, Zeiss lenses perform better than most in low light situations.
For my money - if the flash isn't going to work on the ASUS anyway - then the Lumia may be the better choice.
Then - Nokia just sold it's tablet division to Microsoft. Which probably means the Lumia 2520 will not be supported and it's functionality rolled into the Surface RT.
So in summation:
ASUS isn't supporting the VivoTab RT.
Nokia probably won't support the Lumia because it's been sold to Microsoft.
Microsoft probably won't support the VivoTab RT or the Lumia because they sell the Surface RT.
I initially chose the ASUS because it has 4G/LTE capability. The Lumia hadn't started selling when I purchased the VivoTab RT. The Surface RT isn't really a choice for me because at present it doesn't have the 3G/4G capability.
So speculating here - next year the Surface RT will have 4G/LTE capability as a result of Microsoft purchasing Nokia's tablet division.
So I'm going to return my beloved VivoTab RT - get the Nokia Lumia 2520 and then see what comes down the wire next year.
I hope this is someway helpful to your decision making as well.