I know this has been reported before but I thought to report it again as it's happening with a Tasoth Medic that I captured in my current TFTD game with Illamasqua's TFTD rework v1.3e. I have only ever captured one such alien but have been able to research it and get reports at least 6 times and it's still in my alien containment. I have filed a bug report, hopefully nobody else has.
ps Do all mods have to have "item destroyed" after research is done even for live aliens as I've the option that the body will be added to stores after research activated? Or is this related to the get "one free" part of the research?