The reason you probably aren’t hearing the bass notes with What’s Up (if it’s my post), is because it was created with an NP version of the kit which has the bass notes located in the 62-91 range whereas the Cajon with Bass kit has the bass notes in the 0-31 range.
Try a song that was posted using one of the newer non-NP titled kits and you’ll hear the bass notes. Download, unzip and import the OPB version of this song Sex on Fire - DOP & OPB