UHD Recordings resulting in 0 Bytes files

[Timtam]

Hi,

I got a Raspi 3 with a DVBSky 960 CI tuner with a HD CI Module which decrypts the HD channels for me. We also got an UHD test channel to see if our device supports watching UHD TV, which made me test it with my Raspi. I start recording, the diagnostics page shows valid bitrates around 18000 KBit/s, no errors, no interrupts. The recording file still just is 0 Bytes large, even with some minutes of recording time.

I'm using the latest DVBLink Server Build for Raspi on an old working OpenELEC version. SD and HD channels just work fine.
I started a one minute test recording on 01:24 and attached the log below.
Do you have any idea? I mean, the Raspi isn't capable to process UHD signals in realtime, the CPU is simply to slow, but does this matter? Does it need to process the signal at all instead of simply writing it to the HDD?

Thanks for your help.

Timtam