Reverse lookup occasionally fails for static filters created via Picker  #968

Description

As above and as discussed in https://github.com/orgs/uBlockOrigin/teams/ublock-issues-volunteers/discussions/176

A specific URL where the issue occurs

https://httpbin.org/

Steps to Reproduce

• Add httpbin.org###operations-tag-HTTP_Methods to "My filters"
• Open the logger
• Navigate to https://httpbin.org/
• Click #operations-tag-HTTP_Methods in the logger -- this invokes reverse-lookup code
• Add any cosmetic filter via element picker for the same page
• Force a reload of the page
• Try to reverse-lookup the newly added filter
• Result: no filter list found

Expected behavior:

Reverse lookup doesn't fail and reveals the filterlist

Actual behavior:

Reverse lookup fails.

Your environment

• uBlock Origin version: 1.25.3rc0
• Browser Name and version: Firefox 76
• Operating System and version: Win 10