AI sent out a few rifles where the cocking piece on the firing pin and the safety lever don't play nice and require extra effort to engage the safety or you can't engage it at all, several people on here have reported similar issues over the last couple years. Doesn't seem to be an issue affecting only a certain narrow range of serial numbers, probably a tolerance stacking issue.
With the bolt closed and cocked on an empty chamber, push the rear bolt shroud forward firmly towards the receiver and while holding it forward see if the effort required to engage the safety decreases.
If so, you'll have to send your bolt in to have a few pieces swapped under warranty. Of the 5 AI bolts I currently have, one has a safety that is rather difficult to engage unless I push the shroud forward. I keep forgetting to send it in to have the safety lever swapped. The other 4 engage and disengage with reasonable effort without pushing the bolt shroud towards the receiver.
Keep in mind the AI safety design actually pulls the firing pin back some off the sear when you engage the safety, so the effort is never going to be fingertip easy like a Remington trigger because when you put the safety on you're also compressing the firing pin spring a bit more... but it shouldn't require a hammer or prybar to engage either.