Update on the OneDrive situation:
With some help from a community member, the Arduino developer was able to reproduce the issue. It turns out the problem was not fixed in the beta build of the Arduino IDE but if anyone wants to try the fix there are now a couple versions of the fixed arduino-builder tool available here:
The "arduino-builder-for-1.8.5.zip" is for Arduino IDE 1.8.5. "arduino-builder-for-1.9.0.zip" is for if you're using the beta build of the Arduino IDE. Just replace the file arduino-builder.exe in your Arduino IDE installation folder with the one you find inside the downloaded .zip file.
It sounds like this problem likely won't be resolved in a stable release version of the Arduino IDE until August at earliest because they need to wait for the 1.11 release of the Go programming language, which contains the fix and that release is scheduled for August 1, after which Arduino will need to make their own release of the Arduino IDE using the new Go version to compile the arduino-builder tool. At least there has been some progress on this issue even if the final solution is not soon to arrive.