What shape tool are you using? I have found with very small letters and V shaped engraving tools that the tool can’t go as deep as the top of the V gets too large. You might also want to look at the minimum radius of the cut as again that can stop the tool from being able to move within small pockets.
This one I had to do a separate pocket path for the insides as the main pocket was just missing them completely. Tighter radius and less depth.