(Edit to include relevant link)
I'm pretty consistently pulling 38-48% of DN (and around 5-15% of Sion, higher numbers depends on catching a lucky break and getting some plague early on) with g11 zombie/everybody else g12. And in spite of the mocking from guild and alliance mates, I do have a 6E accuracy arrow on Talia. it really helps, with that 30% bonus I have only missed with her once in 7 raids. (Pretty much my only restarts now are a random DN dispel zombie then annihilate somebody else.)
I feel like I am closing in on a solo too, but I just don't have the offense secondaries across the board (made a decent team for every phase instead of one or two uber teams) to push the huge damage numbers out yet.
I've been cleansing at around 12-15 stacks since that is about as high as my zombie can safely heal the squad (occasionally coin flip on who goes runs that as high as the low 20's, but I try to avoid that).
I've never noticed Talia losing TM as part of a cleanse, are you sure you just aren't pushing it a little too far and not quite getting her health to 100%.
There is also another thread in here where @BOB0_FETT has been doing some amazing solo work replacing zombie with Chirrut, so if you have Chewbacca or BH for phase 3 (or your guild can spare losing a Chex mix team or two) I'd highly recommend giving that a try (gearing up my Chirrut for this, tried last night and couldn't keep it going with a G8 Chirrut).
https://forums.galaxy-of-heroes.starwars.ea.com/discussion/176964/potential-post-nerf-ns-squads-for-p4#latest
