Ok tried the " use a Sledgehammer to tear down a structure while in a FNIX base" ok you got me, knocked down well, generator, power nodules, with 6 star Sledgehammer not completed the assignment, this is the second time for this assignment, last one failed 3 times use the 6 star Sledgehammer twice and the experimental, I knocked down the whole of the FNIX base then the powee generator and the main structure. Same as today’s still did completed tge assignment, so either it doesn’t work, or I miss understanding of what mean by a structure.
Is it possible that the experimental sledgehammer is considered a different sort of weapon than the 1c to 5c sledgehammers?
use any weapon, until 1 final bullet needed, exit the base assault were countdown expires, then re-enter base assault, 
use anything for the final bullet
my assignments are stuck on this and have not updated in at least 48 hours. I’ve used every level of sledgehammer and have never got this particular one to be completed. General consensus on reddit is that it’s bugged for almost everyone.
You just met 2 sledge hammer assignments in a row. This one currently can pop up twice a week, n both can’t complete. Tbh, you can even ignore FMTel atm, not like you can’t get what runner tier reward you without FMTel in a
whole long week with the total time you spent in assignments, especially now FMTel request uneasy hunting very often.
Ok the Sledgehammer assignment on today 10th April just tried it still couldn’t complete it.
I asked the team, what are they classing as a structure, walls, power generator, power nodules, machine gun towers, search lights towers, they all structures. But not got an answer back. Now they use a structure which is singular one.