When playing missions on the legendary level in Roosevelt Island, it often happens that the first three tanks in the mission are invisible - they deal damage, but you can't inflict damage even when aiming at the place where they are shooting from. It always ends in a waste of time because the mission must be started from the beginning.
Had this happen to me at camp white oak didn’t matter how many times I tried and I tried a lot only “fix” or work around was to join someone else’s session and complete it. Granted after doing that I didn’t go back and try again. I needed to finish white oak to clear the invasion to proceed to the league that week.
If you could get some screenshots or video it would help the mods when giving this info to the devs.