rojo: Larian is the one making patches, not GOG.
RSColonel_131st: My understanding is that the offline patches for GOG are created and uploaded by GOG staff. The Galaxy/Steam Patching can be triggered by Larian, but the offline installers are handled separately.
Even if not, GOG would be responsible for recognizing the missing interim file and requesting it. My contract is with GOG, not with Larian.
What seems to happen is that the developer submits erroneous patches and then sends a correction. This is not a problem on Galaxy, but it messes up the GOG patch numbering system for offline files. All the offline patches check that the version they are trying to patch is correct for the patch number. However, if there were ghost patches then the numbering is wrong and the patch refuses to continue.
I have also seen at least one case where the patches were coming so frequently that GOG got behind and just did not supply all the necessary patches.