Ads in 'Pending review'

When your ad is in Pending review, it's because it hasn't been reviewed by Facebook yet. In order to be published, ads need to be checked by Facebook to see whether they comply with the Advertising Policies. Usually, ads are reviewed within 24 hours, but sometimes it can take longer.

A reason why your ad can be Pending review for a long time could be that you have made changes to your ad after you published the campaign. Every time you tweak your ads, a new review is triggered.

If that's not the case, you should read the Facebook requirements and policies for ads. It could be that your ad doesn't comply with the policies and that's why its review is taking longer than usual.

Furthermore, you can always contact Facebook here and ask for a manual check of your campaign in order to know what's going wrong. Sometimes, it can be a Facebook error; if this is the case, then Facebook will unlock the Pending review status.