Typically speaking, you’ll want the RPM to be lower than the torque (power) setting when in cruise. Here’s a screenshot from the 208 POH which shows you the RPM and Torque settings to achieve given speeds at given altitudes/temps.
So what you’ll want to do is look at the RPM and the Torque gauges on the left-side of the middle display and match the figures in the chart, so for example:
Set RPM to 1750, then pull the Torque back to 1800 - this would be a middle-of-the-road cruise when it’s 20C outside. The figures change a bit as the temperature changes, so it will largely depend where you’re flying, but the variation isn’t that much so you can use those figures as a general guide and then adjust as needed for your mission (speed, fuel burn, etc.)
Edit to add: To answer your initial question, this is not a bug - I’ve flown the 208 on a bunch of career missions so far, and if I follow the POH I’m able to match that performance almost exactly.