Long source clip is being trimmed upon upload?

If I opened the properties of the mp4 in my File Explorer, the duration was correct. If I opened it in regular Windows Media Player, it's also correct. 

However, when in the Import screen or source monitor of Premiere, it shows as the 51 min duration (note: after media cache-clearing and attempting to re-import the mp4, the seconds on the imported videos' duration has varied ever so slightly, sometimes 11, sometimes 13, not sure if that's relevant at all). 

After doing more searching online I also tried using Adobe Media Encoder, but even there the browser selection for the video after it processes shows the 51 min duration too, and turning that into a ProRes .mov file didn't bring back the full duration. 

Eventually, I tried fully re-downloading the original video file (it had been shared with me by a coworker via OneDrive and I had downloaded it from there). Thankfully, this new downloaded version of the video file is showing up as full length and imported at full length to Premiere (perhaps the previous download was somehow corrupted?). 

But I have run into an entirely new and I assume unrelated problem, in case you have a suggestion I figure I might as well put it here:

The audio of the video only loads in terms of: when I play the sequence I can hear the audio -- the audio is not all visible in the sequence timeline -- only about 1min 30sec is visible, and then another <30 sec period of audio a few minutes in, rest just has the single blue line, attached some pics to show what I mean  (ignore the video thumbnail, that's in the beginning of the video, not an actual no video symbol).

I have had a different video's audio do this once in the past, and I only noticed when I realized that the transcript and captions I had Premiere generate were missing after a certain duration. To fix that all I did was delete the transcript and captions, save, close the project, reopen it, and then I waited ~20 min and eventually the audio was visible in the timeline, and then I retranscribed and it all worked. 

So, when this video's audio showed up with visual gaps, I just waited for a long time, assuming I must've just moved to quickly with the file last time and it had started transcribing before the audio loaded and maybe that disrupted it. But nothing showed up.

Finally, I closed and reopened the project, and waited another hour. Still nothing, so I saved, then tried opening the essential sound panel, and selected Dialog - Podcast Voice, and let it start trying to "enhance" the audio-- this process went on for a couple hours and got up to 72%, but didn't get to finish (my cat pulled my ethernet, disconnecting me from my VPN and disrupting whole system, and it was time for me to clock out anyway so I just took the L). Not sure if it would've helped but in case it's worth mentioning, while it was going no more of the audio appeared in the timeline visually. 

This morning, I opened the project and the audio still looks the same, which I mostly anticipated, but I was hopingit might appear since I can still play it and hear it so I know the audio is there somehow.

Any suggestions on getting the full audio to load/show up so that I can transcribe?