Reflection capture doesen't update

I believe I am running most recent UE4 version 4.8.1 on Debian 8.0 Jessie x64

Hardware:
Amd fx6300
Nvidia 780Ti (Gigabyte) , with recent 340 driver.
gigabyte 990fxa-ud5
8gb ram

I must say that except reflection maps, everything seems to run perfect.
Today I will also test other card 660Ti I have…

Thank you for quick replay.