I've done as much testing as possible, and I've concluded that it's a problem with THIS MOD ALONE
Most Far Harbor clothing and armors just don't have legendary slots. The marine wetsuit and tactical helm, the lobster trap helmet, the coastal armor, etc.
I distinctly remember a time when this bug didn't exist, and I have a marine wetsuit that I put a legendary effect on a while back, so Bethesda probably fucked something up in an update.
Far Harbor Bugs (1 comment)
Most Far Harbor clothing and armors just don't have legendary slots. The marine wetsuit and tactical helm, the lobster trap helmet, the coastal armor, etc.
I distinctly remember a time when this bug didn't exist, and I have a marine wetsuit that I put a legendary effect on a while back, so Bethesda probably fucked something up in an update.