I had a similar issue – I migrated from dev machine #1 to dev machine #2, and had the exact same environment, software/tools versions, etc. Code coverage worked as expected on dev1, but not on dev2.
The critical difference was that, on dev2, I connected to a vscode workspace that was a symlink of my gopath, whereas on dev1, that path had been a proper directory. When I connected to my vscode workspace on dev2 to the underlying directory, and not the symlinked version, code coverage began to display correctly.
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