You most definitely did not waste anyone’s time, no worries.
My guess why it is working now would really be a mismatch in libraries needed by the compiler, driver and Asan. If you read through the documentation you will see, that Asan has a lot of both soft and hard requirements in terms of environment. That means that I doubt it was a user error but rather lack of proper setup help and documentation.
The preload comment comes from the final Note in one of the official announcement blog posts from Microsoft as well as some other comments I found. In the CLang/gcc world you have the LD_PRELOAD directive that allows you to specify the Asan runtime to be loaded before any other libraries. I am not certain if MSVC has something similar when building from the IDE, but at least you need to disable incremental linking, which is also mentioned in the Docs.
In any case, I am happy that you could resolve your issue! Best of success with your project!