I searched high and low, but couldn't find anything about fixing a cupped strop.

My Hoffritz strop has cupped on the end of the handle. I've tried lathering it and putting it under weight overnight, but when I take it out the cupping is just as happy. Tried burnishing with a bottle, and while the whole strop took a lovely sheen, the cupping remained. Even tried lathering it and forcing it the opposite way. The cupping mocks me.

Now, I'm sure it's not the first cupped strop, and I'm also just as sure that someone has figured how to fix it.

Will someone help me?