Look at your midi options as they may have changed. BiaB and RB can use audio, a midi soft synth or hardware driven synth. When you're playing a file you're hearing audio or (typically) a soft synth. When you're using Play A Chord or Chordbuilder you're using the hardware driven synth.

In midi options there is a checkbox for use DXi soft synth. In your case it is checked but there is nothing selected to play if it is not checked. You need to take the unchecked setting to midi mapper or another operating system midi sound source.

Jim Fogle - 2025 BiaB (Build 1128) RB (Build 5) - Ultra+ PAK
DAWs: Cakewalk Sonar - Standalone: Zoom MRS-8
Laptop: i3 Win 10, 8GB ram 500GB HDD
Desktop: i7 Win 11, 12GB ram 256GB SSD, 4 TB HDD
Music at: https://fogle622.wix.com/fogle622-audio-home