This bug was not present in 1511 version and it appeared when the 1607 version has been released and it is still there on the latest release (1709 version). Glad that it has been fixed on rs4 prerelease.
The license switch options changed per build, they now prolly can release Home/Pro only ISO's and all other sku's will be by either license switch or by dism online/offline set-edition.
There is no mystery or special iso, @mkuba50 explained it, it's all discussed in the pro-ws thread, and shown in mrp reports. There is no license switch to LTSB.