Custom Purge Cache doesn't work!

This feature “Custom Purge Cache” used to work well, but it’s not working for me anymore. For example, when I want to purge cache of a specific CSS style, it doesn’t do that for me anymore, and I have to press purge everything to do it.
How could I solve it? As I mentioned, it used to work before (till a month ago).

Without knowing the actual URL, we can’t investigate. It could still be cached on your server, or maybe it’s controlled by another Cloudflare account.