FMLE and Blackmagic get stuck

Hello,

I am using I7 / 8gb mem PC with BlackMagic Decklink Studio 4K encoder card.

I get a HD feed (1080i) from the SDI BM card, and encode to H.264 rtmp streaming to Wowza server.

When starting MFLE it shows image only on the output preview and not on the input (both are selected...).

When click on the Start button it freeze and show the "application is not responding" massage.

I know the Blackmagic cards and drivers are fine since i can successfully encode with other software (MediaLooks MWriter).

I tried to delete the startup.xml file, and reconfigure from scratch, but every time it get frozen again.

I tried to use different bitrate and with/without audio, but still get frozen.

Please advice.