Bottlenecks are likely to happen in your campaign. You're not doing anything wrong, it's just the way things go sometimes. The important part is bouncing back from issues and making the necessary changes. This is when it really pays to hire an experienced FB Ads Specialist who knows how to recognize the bottlenecks and how to fix them.
I'll break down some of the issues that happen within your campaigns and how to recognize them.
No clicks: your message, creative, or call-to-action isn't resonating with your audience. Or maybe your audience is off. Changes to your ad need to be made to fix this.
Clicks but no landing page views: there could be a number of reasons this is happening. Your landing page could be taking longer than expected to load. Try checking the load time and use smaller images and files if this is the issue. Another reason could be that your audience needs some tweaking.
Landing page views but no add to carts: this could be an audience or landing page issue. Try making changes to your site to make the content more attractive. Also, be sure that your offer on your ad and landing page align. This often happens because of click bait. If this doesn't help, try changing up your audience.
Abandoned carts: are your shipping prices too high? In this day and age, Amazon has people spoiled with free shipping. Try including the price of shipping in your cost and offer free shipping.
Rising cost per click: is your audience saturated? This happens when your audience is too small for your budget and they begin seeing the same ad over and over again. If this is the case, try changing your ad up and see if this helps or adding in new audiences.