While perusing the SPDX generation code, I noticed that here all licenses from files are converted to LicenseRef-style license identifiers. This means that these should all show up in ExtractedLicensingInfo. However, for ExtractedLicensingInfo only non-valid licenses are written here and here, meaning that valid licenses would be referenced via LicenseRef-Identifiers that are never defined.
I don't have a reproducible example yet, as the ones I tried so far don't contain LicenseInfoFromFiles. This may also be the reason why this hasn't come up yet?