I've been around the wiki, and not found any solutions, no problem for my temporal agent or Romulan.
PS. Part way through the Gamma Quadrant, not looking forward to Tenebris torment
Still haven't done Tenebris Torquent, so the secret was actually.
To get Nimbus / Wasteland arc on a Federation Jem'Hadar
Complete the Klingon war arc as a side arc starting with Diplomatic Orders from Admiral Quinn...
Stranded in space, Researcher rescue, contact then changes to Burgess in available, but follows on if you do not break out of the mission path.
Secret Orders, The Doomsday device, The Galaxy at Large (report to Admiral Quinn at spacedock)
Franklin Drake will now be "Available missions" contact for The Secrets of Nimbus
(writing out in full so it should help if picked up in search)
It should unlock at level 65, after you have chosen your faction and put your 20 hours into the character. It is in the “Available” tab of your mission journal. If you don’t see it, you may need to do the mission called “The Galaxy at Large” in the standard mission journal. “Galaxy” is just a wrapper mission that used to be required to open the other tabs in your mission journal. So you sometimes can’t start missions until it has been completed.
Answers
Hope you can find it!