I highly recommend you email a report of this directly to IDM Support.
This forum is a "user-to-user" forum, and IDM does not regularly monitor this forum, so they most likely will never see the post. It needs to be reported.
This should be fixed.
Understand, though, that in the world of portable apps, there are varying definitions of portability. The most common definition is that it is able to run from a portable drive without any restrictions on whether or not it leaves data behind on the host computer. Some software will go so far as to state it is both portable AND "stealth", where stealth means it leaves no trace that it was ever there. It is important that an "administrator's toolbox" be filled with quality, useful tools that are both portable and stealth. Since there are other portable editors out there that are also stealth, IDM needs to get this oversight corrected in an upcoming release.