April 2017 - last edited April 2017
Same with me. I leveled up my first strike team in the app and didn't get the achievement. Thinking that was the reason, I made a second strike team and only handled them in game. They just reached level 20 and I still didn't get the achievement. I have a third at lvl 15 but if third time isn't the charm I'm just going to give up until Bioware announces a patch that specifically mentions this issue.
Okay, I got the achievement. For whatever reason it popped up a couple hours after I reached level 20 randomly when I was debriefing my lower level team (the 15 one).
Same here on Origin on PC.
Used the Apex app until level 19, then tried in game for level 20 and it didn't register. I had a second team level up to 20, still no achievement.
I also have 6 Strike Teams and the Teamwork achievement is not showing up either.
Well got the same problem as you guys. First team got 20 lvl from the app, second from the Tempest terminal, third is came from Nexus... and still got none. Maybe fourth will working from multiplayer menu? Some people says that they played multiplayer and after extraction in random time they got it, some says that they just used 20lvl squad for mission then get it after debrief... this is ridiculous.
Like many above, I had my third team reach Level 20 yesterday and no achievement yet. I made sure to deploy and debrief the team on Tempest, so looks to me like that might not actually be a workaround.