<p>I'm trying to print <a href="https://www.thingiverse.com/thing:4461654" rel="nofollow noreferrer">a gear for a robovac deal</a>.</p>
<p>The issue I'm having is with gaps between the walls of the top part of the gear. It needs to have the corners filled to provide stability or else the tabs easily snap. I've tried adjusting the nozzle size, line width, filter gaps and print thin walls but seems to slice with variations on the same issue. Is this a Cura issue? Is there anyway to slice and print this to fill those gaps?</p>
<p><a href="https://i.stack.imgur.com/0g7zy.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/0g7zy.png" alt="gear with gaps between walls" /></a></p>

The problem isn't Cura, rather its the precision of the 3D model. If parts of the model is smaller than the line width the model cannot be printed. A solution to this would be to increase the thickness of the cylinder, decrease the size of the square or reduce the line width to allow that region to be properly fabricated, another solution would be to decrease the line width (line width option) however, keep in mind that you should not reduce the line width beyond the nozzle hole size (nozzle hole > line width). As mentioned before, if the model requires sections that are smaller than the line width, Cura will ignore it. From the image you provided it would seem that the corners are extremely close to the wall of the cylinder which prevents Cura from making a extrusion path, the reason of which I explained above.