I’ve been reading a lot of complaints about the lack of legendary drops from Iwajira and just want to recommend a better alternative: Flameknuckle in the Badass round of the Holodome. Two will spawn in the fourth wave of the fight and have a very high chance of dropping a Nukem.
An excellent Rocket Launcher or Grinder material if you prefer.
The Iwajira who used to drop a Thingy every fight is never coming back. Time to move on.
Something I did when I reset my UVHM playthrough was go through the story until you meet Flameknuckle for the first time, kill him, loot the Nukem, quit, and reset the game again. Did that 5-6 times to get some grinder fodder. It’s pretty quick, and VERY easy. 
Excellent method too if you’re leveling using the opening mission. How long would it take you?
Your guess is as good as mine for the leveling part: I was already at level 70 when I did that 
But getting 4 Nukems took me less than 45 minutes.
That’s a pretty good rate.
If I want legendaries to grind, I just farm Drongo Bones for a Fatale, he is pretty generous with those and he is close to the fast travel in Outlands Canyon.
Even with this increased drop rate, I’ve farmed Iwijeiajeiane 100+ times and I haven’t seen a single Thingy drop in any of them. TBH I don’t think they’re going to do any more events so whatever issues they had that made them change his drops, I hope that they revert it back to what it was pre-holiday event but that’s probably just wishful thinking.
EOS is my go to for Legendaries. Drongo et al do not guarantee leveled drops.
+1 to flameknuckle and reset uvhm.
well I’d best get a few before they decided to ‘fix it’ and ignore the glitches that actually need fixing.