While on paper SATA is hot-pluggable, in practice, as you just found out, that's not always the case. If you want to hot-plug drives, you may want to use hot-plug trays. -- Wacky Races 2012!
Well hot-plugging has worked reliably on this system since I bought it, so I'm inquiring about the sudden loss of this ability. I never experienced a single hot-plugging problem before a couple of weeks ago, so I'm wondering why problems would've suddenly started.
There are so many things that can go wrong during hot-plugging -- starting at the physical level -- that I won't even bother to go into details.
There is a very good reason why hot-plug trays and enclosures were invented.
BTW, until last week, I had no problem with hot-plugging a debug connector to the device I work on, but then one time I managed to burn up both male and female connectors -- several neighboring traces disappeared without a trace.... -- Wacky Races 2012!