Where are you flying from?
What's missing?

Once US custom in SJU couldn't figure out how to use luggage strip and lose mine and I didn't know until the luggage arrived in YYZ. (how do I know is US custom? Cuz they leave me a note inside the luggage)

The other time was at HNL to NRT, even worst, they didn't put things back in order (and ripped open an unwarpped gift because someone is too lazy and damaged the box) and therefore my luggage cannot be close (TSA lock was build-in on the case) and they just warp it with duct tape. And again the luggage strip was missing. When I see my luggage at NRT, I was like W-T-F, it was half open and anything could of fall out in transport. Glad I didn't notice anything missing because I pack everything in bags and no small loose items.

Since then I longer use luggage strip, when possible I just ask for tapes at check-in desk.

Back to OP... Since I don't know where you are flying from or what's missing. It maybe possible custom took it but you should have a note inside your luggage.