I built a new PC about a month ago.  Reinstalled everything , copy& pasted my old CDLC into the new file, have Cherub Rock, have the D3D dll in place.

Initially, right after the build, the songs would populate but the game would lock after tuning the guitar.

Now, only 2 of over 200 songs populate in game, they're still playable.  I don't have any in-game filters turned on.

If anyone can provide some insight into getting this running again I would greatly appreciate it.

There could be a few causes for this.

Does cherub rock and the on disc songs still appear?
If the on-disc songs don't show up it's probably a filter issue, check in the score attack menu instead and see if they show up there.
If cherub rock doesn't show up (with no filters) neither will the custom songs. Uninstall and reinstall it and check it appears in the dlc folder.

The songs freezing after tuning is because the .dll is installed in the wrong place or has been renamed. I'd reinstall it: https://ignition4.customsforge.com/tools/CDLCEnabler