Charlie,

I had a chance to look at this closer tonight --- it's a little more complicated than I thought earlier.

I record files as either .MP3 or as .WAV in BIAB, but also some likewise recordings in Reaper.
I haven't seen any problems opening files in Reaper itself, whether they are Mp3 or WAV, and originally from either program.

I now see that when I try to import a .WAV file originally rendered from Reaper, into 64-bit BIAB Audio Chord Wizard, nothing happens --- no import.
If the Reaper file is rendered as a .MP3, it imports into ACW just fine. This is 64-bit BIAB.

However, when I switch to 32-bit BIAB, those .WAV files from Reaper import into ACW without any problem! As do the .MP3 files from Reaper.
A bit convoluted, I hope I'm explaining this accurately.

I'd say that 64-bit BIAB has something going on that prevents ACW importing .WAV files from Reaper recordings. No problem at all with 32-bit BIAB.

Jerry
2019 BiaB Megapack (634), RB 2019 (Build 4)
Reaper 5.983 x64, Audient id14 USB interface, Voicemeeter Potato 3.0.0.8, Nektar LX49+, Roland E20
i7-6700K Skylake desktop, 64bit Win10 Pro(1903), 32GB ram, 512GB system SSD + 2TB data SSD