I tried all of the different ones available, but still could not import the audio. When I try to import the AVI file, the video attributes are displayed, but the audio attributes says: "Stream attributes could not be determined". See screenshot.

Oh, that's something different.

Your audio may not even be compatible with the AVI format. There are many such cases.

https://www.vegascreativesoftware.info/us/forum/faq-how-to-post-mediainfo-and-vegas-pro-file-properties--104561/

I think it's compatible since I can play it without issue in several video players.

Here is the MediaInfo Data.

General
Complete name                            : F:\Untitled 03.avi
Format                                   : AVI
Format/Info                              : Audio Video Interleave
Format profile                           : OpenDML
File size                                : 1.27 GiB
Duration                                 : 56 s 423 ms
Overall bit rate                         : 194 Mb/s

Video
ID                                       : 0
Format                                   : JPEG
Codec ID                                 : MJPG
Duration                                 : 56 s 423 ms
Bit rate                                 : 191 Mb/s
Width                                    : 1 920 pixels
Height                                   : 1 080 pixels
Display aspect ratio                     : 16:9
Frame rate                               : 59.940 (60000/1001) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:2
Bit depth                                : 8 bits
Scan type                                : Progressive
Compression mode                         : Lossy
Bits/(Pixel*Frame)                       : 1.539
Time code of first frame                 : 00:00:00;00 / 00:00:00;00
Time code source                         : Adobe tc_A / Adobe tc_O
Stream size                              : 1.26 GiB (99%)

Audio
ID                                       : 1
Format                                   : PCM
Format settings                          : Little / Signed
Codec ID                                 : 00000001-0000-0010-8000-00AA00389B71
Duration                                 : 56 s 423 ms
Bit rate mode                            : Constant
Bit rate                                 : 2 304 kb/s
Channel(s)                               : 2 channels
Sampling rate                            : 48.0 kHz
Bit depth                                : 24 bits
Stream size                              : 15.5 MiB (1%)
Alignment                                : Aligned on interleaves
Interleave, duration                     : 1008  ms (60.39 video frames)

Here is the Vegas Info:

General
  Name: Untitled 03.avi
  Folder: F:
  Type: Video for Windows
  Size: 1.33 GB (1,365,741,568 bytes)
  Created: Tuesday, February 4, 2020, 7:45:08 AM
  Modified: Tuesday, February 4, 2020, 7:46:05 AM
  Accessed: Tuesday, February 4, 2020, 7:46:05 AM
  Attributes: Archive

Streams
  Video: 00:00:56.423, 59.940 fps, 1920x1080x24, Blackmagic 8 bit MJPEG Codec
  Audio: 00:00:00.000, 48,000 Hz, 24 Bit, Stereo, Uncompressed

ACID information
  ACID chunk: no
  Stretch chunk: no
  Stretch list: no
  Stretch info2: no
  Beat markers: no
  Detected beats: no

Other metadata
  Regions/markers: no
  Command markers: no

Media manager
  Media tags: no

Plug-In
  Name: aviplug.dll
  Folder: C:\Program Files\Sony\Movie Studio Platinum 13.0\FileIO Plug-Ins\aviplug
  Format: Video for Windows
  Version: Version 13.0 (Build 943) 64-bit
  Company: Sony Creative Software Inc.

Just for fun, try 16 bit 48Khz PCM audio for your source.

That's what audio for video delivery gets converted to anyway.

Unfortunately, playing in VLC or other players has absolutely nothing to do with decoding for editing in Vegas, which can be picky about audio.

The 16 bit 48Khz works. No issues with that.

Yes, that is the AVI spec, although players are generally more forgiving. Hope that is a good solution for your needs.

BluRay spec allows for high-bit audio, in many cases.

I realize I wasn't clear in my last response. The 16bit audio that I used was just some test audio that I was able get. BMD Media Express only records at 24 bit doesn't and allow me to specify at what bit rate the audio is recorded. Is there any way to import the 24 bit audio into Vegas? If not, is there a program you recommend that can transcode the audio to 16bit?

Audacity might do it and is a useful free download.

I realize I wasn't clear in my last response. The 16bit audio that I used was just some test audio that I was able get. BMD Media Express only records at 24 bit doesn't and allow me to specify at what bit rate the audio is recorded. Is there any way to import the 24 bit audio into Vegas? If not, is there a program you recommend that can transcode the audio to 16bit?

Can you switch from AVI to another container format?

You might try Import Assist in Happy Otter Scripts.

A feature request to Magix pending other solutions might be a good idea.