A Microsoft file hosting and synchronization service.
I did as you requested. The links seem to work for a while but break later. I noticed the Source File uses the OneDrive location even though my Spreadsheet is on my local drive. I'm guessing that's the problem - the OneDrive location changes arbitrarily and that breaks the links. I've tried hitting the Change Source button and pointing to my local file. It shows that file in the Source file field but when I hit OK, it says the source file cannot be found.
I've tried many options to fix this (some with the help of AI) and nothing seems to work. There are other posts talking about this same issue. Gemini (Google's AI tool), after sending me down the wrong path several times concluded that there is not workaround except moving the files out of a location managed by OneDrive. I'm surprised that there's not a problem documented with a time for a fix. I pay for an Office 365 subscription. This is the first time I've asked for help and am disappointed with the lack of support to fix, or at least, acknowledge the problem.
As I originally stated, this is are recent problem - starting sometime in August. Prior to that, it worked fine. This has caused me a lot of wasted time and effort trying to fix the problem. Now I just paste the values in every time my Excel values change - which is a lot of manual effort that should not be necessary.