I highly recommend tenting your Ergodox (at an angle anywhere from 15–50°; angles steeper than 30° are generally more comfortable but people tend to reject them for seeming unusual; try out a few different angles and then stick with whatever seems most comfortable to you) instead of leaving it to sit flat on the desk. There are many possible ways to prop it up at an angle in such a way that it will sit still solidly and not slide around, but since the structure for that isn’t built in, you’ll have to DIY.