After creating the Facebook ad, I opened the Facebook Power Editor. I made sure that the ad will run under the same campaign and ad sets.
I also changed the target audience.
I re-copied and re-pasted the existing Facebook pixel to my Tumblr thank you page.
After setting the rest of the details, I uploaded the changes.
A few minutes later, I saw a Facebook notification saying that my ad is pending review. That was weird; I never saw any notification from the first Facebook ad that I did. Anyway, since I saw a notification, I am now more confident that my Facebook ad’s future is brighter than the first.