Element Picker and Zapper Mode not working on Thunderbird RSS Feeds

[click-click]

Prerequisites

• I verified that this is not a filter issue (MUST be reported at filter issue tracker)
• This is not a support issue or a question
• I performed a cursory search of the issue tracker to avoid opening a duplicate issue
• The issue is not present after wholly disabling uBlock Origin ("uBO") in the browser
• I checked the documentation to understand that the issue I report is not a normal behavior

I tried to reproduce the issue when...

• uBO is the only extension
• uBO with default lists/settings
• using a new, unmodified browser profile

Description

Element Picker and Zapper modes do not work on RSS feed content viewed in Thunderbird. If I enter About Thunderbird and select the Releases link. picker and zapper work fine.

A specific URL where the issue occurs

http://feeds.feedburner.com/TheWindowsClub

Steps to Reproduce

Create an RSS feed in Thunderbird from the URL above
Select one of the listed entries to be viewed
Select element picker for that content
Nothing happens

Expected behavior

I assumed element picker and Zapper modes worked the same as in Firefox. If I select the link of the RSS feed entry, the content can be shown in Firefox and it displays the same as it does in Thunderbird. The only difference is the the picker and zapper modes work with Firefox, but not with Thunderbird.

Actual behavior

Element Picker and Zapper Modes do not react/work on any RSS Feed content in Thunderbird

uBlock Origin version

1.37.2

Browser name and version

Thunderbird 78.14

Operating System and version

w7, w8.1, w10

[gwarser]

Duplicate of #825

[gwarser]

Create an RSS feed in Thunderbird from the URL above
Select one of the listed entries to be viewed
Select element picker for that content
Nothing happens

This works for me:

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My uBO is 1.38 and Thunderbird 91.1.1, so maybe this is: "Because support for WebExtensions in Thunderbird is still a mess. #194" in 78.

[click-click]

I tried the v93 portable beta version and picker and zapper modes are working there, so I guess you are right about WebExtentions being messed up in v78. Thanks for testing. Will wait till the next portable v91.2 ESR is released.
Thanks for taking the time to test and verify.