I previously attempted contact with you via Twitter. I got this issue by running a 4k60 (3840x2160) Prores LT video from an Atomos Ninja Inferno through Voukoder 1.1. I punched in the generic settings for 4k60 from this page:
And then got an error "Selector:9 Error Code: 3", which I thought was odd, so I tried updating to 1.2.
I wasn't previously having this issue with 1080p60 video with the same settings. Haven't tried encoding another 1080p60 video again but I will try again if need be.
One other important thing to note is that the Export menu is taking a significantly longer time to show up (or sometimes won't show up at all) after I installed the update.
Please let me know if this is enough.