Re: S-5 Training Session - Unable to unlock although completed milestone
Issues with getting the rewards of completing a milestone is something that has plagued this game since the very beginning. Your case is probably another instance of this issue. There's this report which compiles milestone reward issues since 2017, and may have a method that fixes the issue for you: https://answers.ea.com/t5/Bug-Reports/Unable-to-claim-reward-although-I-ve-completed-the-milestone/m-p/6500879
Unfortunately I don't know the suggested methods, nor where exactly you can find them in that almost 200 pages long report, but I remember seeing suggestions there.
Also, recently EA has given us news on the milestone reward issues:
@EA_Atic wrote:Hey everyone!We have done a back-end update that should help out with Milestones not restringing, log into the game and you should see a notification for completing the milestone and get the rewards related to to the milestone.To get the milestone to show as 105/105 etc, you are going need play a few rounds and everything should sync up for you.Thank you for your patience!/Atic
Although this message was specific to the Offensive Formation milestone (which bugged for most, if not all, players since it was released), we can hope it'll address all other milestones and the milestone reward system as a whole, which has been bugging since Day 1.