Diff-update not working for manually added filter lists #3028

Prerequisites

• I verified that this is not a filter list issue. Report any issues with filter lists or broken website functionality in the uAssets issue tracker.
• This is NOT an issue with YouTube, Facebook or Twitch.
• This is not a support issue or a question. For support, questions, or help, visit /r/uBlockOrigin.
• I performed a cursory search of the issue tracker to avoid opening a duplicate issue.
• The issue is not present after disabling uBO in the browser.
• I checked the documentation to understand that the issue I am reporting is not normal behavior.

I tried to reproduce the issue when...

• uBO is the only extension.
• uBO uses default lists and settings.
• using a new, unmodified browser profile.

Description

Since the last stable update uBo is supporting differential updates.
I added my own list with differential updates available in the header, but it doesn't update after the diff-expires.

A specific URL where the issue occurs.

manually added filter lists

Steps to Reproduce

1. Make your own list and add in the header

! Title: Example Filter List
! Last modified: Fri, 15 Dec 2023 09:35:24
! Expires: 14 days (update frequency)
! Diff-Path: patches/2023.12.15.575.patch#list3
! Diff-Expires: 12 hours
! Description:  
!     A text
!    which is nonses
! Homepage: https://github.com//Personal-List
! License: https://github.com//main/LICENSE

2. Add this list to uBlock
3. see that it doesn't update after 12 hours, also not if you restart your browser.

Expected behavior

Manually added filter list should also update on diff-expires

Actual behavior

uBlock is not using differential updates for manually added filter lists (???)

uBO version

1.54.0

Browser name and version

Firefox 120

Operating System and version

Windows 10, 22H2