Hi !
I'm still unsure why, I've compared voltages on boths ShakeIt and Simhub everything is the same,
The only difference is the suggested wiring, in the original ShakeIt I was suggesting to get the motor ground to the center pin (common ground) where in Simhub doc I suggest using the +/- dedicated to a motor. I know this trick was giving some extra power but it was risky (only a little error in the wiring and you would get a short), that's why I removed this suggestion, however it's still possible to do it. Did you changed the wiring when you switched to Simhub ?
I made some additional tests this morning, by removing the "anti-humming" code I got some extra power. I made a version where it is disabled by default :
https://www.dropbox.com/s/8bljkly9nvfbx55/DisplayClientV2.rar?dl=0
Simply overwrite the file in C:\Program Files (x86)\SimHub\_Addons\Arduino\DisplayClientV2 and reupload using the setup.