Layers disappearing when connected to null via Parent pickwhip

When linking layers to a null controller via the Parent pickwhip, the layers disappear. I'm using AE 25.6. This has never occurred in previous versions for me. I noticed similar earlier posts about this glitch and the issue was that the user was connecting to the null via the Track Matte pickwhip. I am using the Parent pickwhip. Can someone suggest why this is happening? Thanks!!