Several TikTok Ads campaigns I ran completely failed and lessons learnt afterward

I'm not here to share tips, just to recount a recent experience running TikTok ads. I had a few campaigns that, at first glance, everything seemed "okay": creatives were good (based on successful ones), offers weren't bad, setup was normal but the results were almost nonexistent. Some campaigns got approved but hardly spent any money. Others ran well for the first 1-2 days then dropped sharply for no apparent reason. Even testing the same creative across multiple accounts showed significantly different performance. Initially, I thought it was because the creatives weren't good enough. But after a few such instances, I realized it wasn't simply about creativity anymore. The difficulty is that sometimes it fails without a clear reason. It's not like "bad creatives" or "wrong targeting," but rather that there are underlying factors like account trust, learning phase, delivery that I can't fully control. Previously, I focused quite a bit on testing creatives and scaling. But lately, I feel like a large part of my work is figuring out why things aren't working, even though everything seems fine. I'm still struggling with these kinds of cases. I wonder if anyone else working on performance, especially TikTok ads, has encountered a similar situation? How do you usually handle these "unexplained failures"? Or do you just ignore them and try something new?