Not sure if I completely follow, and I haven’t run that version of Maya with the extension yet, but I tried exporting an animation from 2016, and it went flawlessly, which tells me it’s not an issue of the command being deprecated.
Make sure you have the FBX plugin loaded. It likes to unload itself sometimes. Just unload and reload, and if it still doesn’t work, back up your prefs, then delete them and restart. It definitely seems like an issue with the FBX plugin though.
I tried importing from an FBX exported from the engine animation starter pack (4.8.1) and it worked flawlessly as well (except the animation had some bad twist settings!). One more thing, in 2016, and possibly 2015 ext 1, I had to change the default FBX exporter to use 2014/2015 FBX, as I found while testing something for someone else, that the engine doesn’t seem like it fully supports FBX 2016 yet and won’t properly bring in files. Dropbox - FBX_Import_Issue_RESOLVED.mp4 - Simplify your life?