- Have you tried to set the CC1101 in TX to see if the spectrum is as expected on the failing boards?
- Are you sure that the failures comes from poor grounding? The gerber plot you have included looks good. If there is a problem with the soldering it could be wrong amount of solder paste.
- It looks like the ground plane is cut on 3 sides by routing. Do the decoupling caps have a short return path to ground?
In general it would be useful to find/ know exactly what causes the receive to fail.