Ok, I think I figured it out. @labs118
Installed a fresh instance of Firefox 52.9.0 ESR in a sandbox, installed ABP 2.6.13, but forgot to dig into the FF settings and internal settings before installing ABP, so didn't disable addon auto updating before ABP updated itself to ver 3.5 which is that interface you see. I tried a few tests with ABP 3 versions and it looks like the problem only occurs using the newer Adblock Plus 3 versions (the whole thing was re-written for FF Quantum and something changed). Issue does not manifest if I use the older ABP 2.6.13 version
(Newer ABP 3.x versions: They are awful. Just awful. Almost all control over ABP is taken away. Access to see what is being blocked, ability to easily easily tweak/enable/disable individual rules, etc. It looks like it caters to people who are going to just use subscription lists, take what's dished out to them. and not use ABP manually in any way - as I do exclusively. Totally useless for my needs. If forced to upgrade to ABP 3 series at some point I will be jumping ship to something else.)
In any case - I now can see the fail, it is exactly what I thought it was based on the reports here, and nailed down the rule causing it.
This element hiding rule in the Easylist ruleset:
ebay.com#?#li.s-item:-abp-has(.s-item__title-tag)
uses ABP extended* CSS selectors, and is intended to disappear all li.s-item parent elements that have any child element with a "s-item__title-ytag" class attribute.
I think it's a mistake. It looks like it's too broad because it may be missing a child selector which is probably critical because it is using the -abp-has special qualifier - what it ends up doing without further refinement is wastes any li.s-item parent element that contains any child element with a ".s-item__title-tag" class attribute (which are probably the ads it is supposed to target). Something isn't working right, and the search results (which are contained in li.s-item elements) are getting hidden too.
(I didn't see what the point of that particular is on the eBay pages I viewed, as I was looking at getting it to even occur and then circumventing it more than figuring out their rule, don't have all my tools installed in that temporary Firefox instance, the ABP interface is useless for that as I ranted above, and debugging in that browser instance is agonizing)
[*Those extended selectors ARE very cool because they allow you to disappear a parent element CONTAINING something you use as a selector target. Regular CSS3 (like I use in stylish rules) only allows you to disappear the actual target of the selector, which often doesn't do the trick.]
In any case, a way to fix this is to over-ride that rule with an exception rule. Add these 2 rules to your filters in ADblock Plus (or any adblocker like uBlock Origin that is seeing this issue) and I think that should fix it:
ebay.com##div#adBlock
ebay.com#@#li.s-item:-abp-has(.s-item__title-tag)
The first one takes care of some ads that might get shoved in below or mixed in the results, and the second one is an exception rule that should override/negate the Easylist rule causing the trouble.
Once those 2 new rules are plugged in, Easylist can be turned back on. I hope. Worked for me.
Once a few of you try this out and it works, I guess I'll report this to the Easylist folks (even though I really don't want to - lazy and have no skin in the game). They can change/remove/fix the rule, and once ABP (and other) Easylist installs update automatically (or manually) it will be a non-issue. Once Easylist fixes it, those 2 added rules can be deleted (or left- they should so no harm unless they conflict with the revised Easylist rule) @eburtonlab
[Addendum: looks like someone already reported it on the Easylist forums last night - hopefully action will be taken]
I might look at it a bit more to try to figure out exactly WHY that Easylist rule is not working right, because understanding that will help in determining if the workaround rules I posted above are sufficient, and help determine if it is indeed an Easylist rule syntax or logic error, or if there's a bug that got introduced in the Adblock Plus 3 versions (problem doesn't manifest when using ABB 2.6.13 when using the same Easylist ruleset - could be the way the ABP v3.x handles the rule).
Further scrutiny may also help determine if eBay had anything to do with this. At this point I don't think so, but SOMETHING changed in the last week or so that caused the problem to manifest. Latest version ABP 3.5 released 3/12/19 and ABP v3.4.3 I also tried released 1/23/19 - those updates don't fit with the bug surfacing this week. Don't know when the bad rule was added to Easylist. But some change somewhere caused the false detect (either a legitimate, subtle eBay change in the search pages, or an addition of that Easylist rule or a change to that rule.)
TLDNR:
One of the rules in the Easylist subscription adblocking list used by AdblockPlus, uOrigin, Adblock, etc is overly aggressive and is hiding sold and completed search results. A temporary fix until Easylist fixes it is to manually add the 2 rules posted half a page above to your adblocker rules.
