I'm not sure if you can use virtual cores to mine in fact I suspect you probably can't. They can help with things like video encoding but I would ensure you are only using actual real cores to mine.

So it looks like you have 12 real cores. That should be the max core number you should use but due to reasons I will suggest you might be better with less cores.

For example I've also heard that you need a lot of RAM for mining STEEM and there may be a minimum that is required per CPU core - so that may be another factor that may actually limit you further - the fact that you are only getting about 38Khps it may be that you only have enough Ram for about 5 cores to mine.

Another thing I though of was cooling - generally CPUs with higher core counts (6+) tend to have lower maximum clock speeds and they may also throttle down more easily because of the greater heat density. It might be worth checking to see what kind of temps the cores are running at - mining may be causing excessive throttling of your cores. I know there is plenty of software to monitor these things in windows but not sure about Ubuntu.

As an experiment it might be worth starting with a config of 4 cores and testing to see what kind of results you get in terms of hashrate, then gradually increasing the core count until you stop getting any increase or even get a decrease.

The other thing is it may be a VM problem. I'm just running directly in Ubuntu so can't really comment on that - but if it is a dedicated mining machine you could try a direct ubuntu install - you could even make a separate partition to run it on.

The fact that you are getting a hashrate, estimated time to block and witness information suggests to me that mining is actually occurring so it may just be that you have been very unlucky in not getting a block to solve. I would still try the things I've suggested above though because you may end up getting better results and a higher hashrate.

If none of the above works I would suggest posting again