Hey Bigdabill7, I can help you.
To summarize, OneDrive (when you activate it) default saves files to the cloud. That means even the save game files in the "My Games" folder. For me, I almost always disable OneDrive because it is an extra drain on resources I don't need, but when I do that then it cuts off my access to the cloud. You see, the annoying thing is that once OneDrive has auto-saved your data to the cloud, then you need to be connected to the cloud to access it because it pulls it off your machine to save space.
My solution is this:
1. Make sure that OneDrive is on, first of all, and that your files are indeed accessible.
2. Right click on the save game files, and any other files you want to access while offline or not connected, and choose to "save to the machine." I don't remember if that is the exact terminology, but it is something like that.
3. Enjoy Mount and Blade again!
I scratched my head for months trying to figure it out, but I finally had a flash of insight one day when it magically worked (I was stoked), I turned off OneDrive, and then it went back to not working, much to my puzzled disappointment.
Here are a couple links which might help you understand more:
Learn how to choose the location where your files are saved by default.
support.microsoft.com
I hope this helps for you!