Can any developer let us know the specific actions you need to take in order to get cover up done? Ive taken Bari and have bombers constantly bomb it but no friendly ships appear at the harbor and no dialogue from the generals about impending bombings. 

Ive restarted the campaign at least 20 times and done a million different things recommened by others. Capturing Potenza first, capturing the airfield near Salerno first, rushing airborne troops to Bari, having the game on expert so the enemy can retake Bari, taking Naples after taking Bari, not pushing too far North so the bombers dont leave, and even not taking any major town other than Bari. Its my only achievement that I need and its been irritating that nothing can trigger the side mission for it. I am also on console, specifically Xbox Series X.