Office 365 / Office 2019 license conflict, Onedrive issues

Hi,

My Office apps were bugging me that they "May not be genuine". That's weird, I thought, I'm pretty sure I bought a license for these a while back. Not bothering to verify this, I then went out and purchased Office 2019 Home/Student, which I understand is not a subscription but an outright purchase of these apps. I went home, followed the install instructions and when Excel opened up I was greeted with an "Office 365 - Excel" splashscreen. Previously I had been getting what seemed to be an Office 2019 or 2016 splash screen. Nevertheless, I now seemed to be "genuine". I checked my MS account and then realised I had a previously purchased a 1 year subscription to Office 365. So I have 2 licenses now that look like this:

But when I tried to open a document from Onedrive, Excel crashes immediately. Looking online, seems like this is a common problem with Office365 apps vs. Onedrive documents. So I figured I'll try to uninstall this Office 365 and get Office 2019 installed. But after uninstalling Office, and reinstalling from the Office 2019 download, it still shows Office 365, and has the associated Onedrive document issue. Not only that, but after reinstalling it is now telling me that my license "May not be genuine"!

How can I remove any traces of this "Non-genuine" license? And how can I force the install of Office 2019 instead of Office 365? Do I even understand what the primary issue is? Considering I've double-paid for this software and it both crashes and accuses me of being a fraudster, I'm just a tad frustrated and disappointed with this situation.

Please don't tell me to install a fresh copy of Windows to solve this issue.