Actually the problem is not with Transcend, it's with Apple for making the kext signing apply to only Apple labeled devices:
https://forums.macrumors.com/threads/1807889/
We all should sign this petition:
https://forums.macrumors.com/threads/1816557/
And as of right now, the best answer for those of us using third party SSDs is Cindori's TRIM Enabler.
Lou
Thanks Lou. I just submitted my feedback to Apple. FYI Cindori TRIM enabler brings up other issues, not least of which is OS upgrades which he warns about. The other kinds of issues I've had with it are sleep/wake not working properly, drive acting flakey, sometimes even slower then simple not enabling TRIM at all. If I had known that TRIM would break when I bought the Transcend drive I would have just bought a Samsung OEM drop in replacement on Ebay (costs twice as much, but Apple sees it as it's own supported drive).