You cannot play/edit this mission, error | Need Help

[Huey]

I've had this issue for a while now but I've kept putting it off, but every time I try playing the campaign, or a scenario such as the new Oldman scenario, where if you die you have to revert the save, this error comes up.

"You cannot play/edit this mission; it is dependent on downloadable content that has been deleted.ace_common, ace ballistics"

In order to continue playing the mission I have to go back to the main menu and restart the entire mission or scenario making it very frustrating to continue playing. Just before writing this I tried starting a new campaign mission from the very beginning of the campaign, and it also gave me this same error.

Now to start off, I don't have any ACE mods activated (and I'm not trying to play with any), and I've reverted all my missions for a fresh start, I verified my game cache, and mods with still no effect. I also reinstalled my game completely, along with all the mods off of the Steam Workshop again and I'm still getting this error.

I did research beforehand into this issue but I couldn't find anything that specifically pertains to this. I just need help solving this issue, since I'd really like to play the entire campaign without having to restart the entire mission. And I'd love to try the new scenario without losing hours worth of effort into it.

Thank you for your help.