There are two things known to break drag and drop.
1. If BatchPatch is running with elevation as administrator, drag and drop will not work. This is due to how Windows works and cannot be fixed/changed.
2. If you have renamed BatchPatch.exe to anything else, drag and drop will not work in the 20170713 release (or older versions) of BatchPatch. However, this will be fixed in the next release of BP either late 2017 or early 2018.