My ads have been active for days but I'm not receiving any impressions. I've significantly raised bids ($3/4cpm) and also tried ocpm campaigns. I'm not running anything shady so I really don't get why this is happening. From a quick Google search it seems like it is quite a common thing...
Need more info.
What demographic? Targeting? Audience size? Ad group budgets?
Have you checked that the campaign, ad groups, and ads are all set to active?
$3 cpm isn't really all that high. I'd be willing to bet that if you bumped it to $30 bid on a small budget you would receieve impressions.
Do you have a click bait headline? They have been denying impressions to ads that are extremely clickbait-y on occasion lately