[Affected versions]:

• 67.0b6
• 68.0a1 (2019-03-28)

[Affected platforms]:

• Mac OS 10.11
• Windows 10 x64
• Ubuntu 18.04 x64

[Steps to reproduce]:

1. Go to https://addons.mozilla.org/en-US/firefox/addon/evernote-web-clipper/?src=cb-dl-users and install the add-on
2. Open about:addons and click on the Preferences/Option button for the installed add-on
3. Toggle between Allow/ Don't allow buttons from Run in Private Windows section

[Expected result]:

• The content inside the "Default clipping account" panel is clear and visible.

[Actual result]:

• The content inside the "Default clipping account" panel disappears.

[Regression range]:

• I will determine one asap.

[Additional Notes]:

• After refreshing the page, the issue is fixed.
• The issue is reproducible regardless if the "Allow this extension to run in Private Windows" is selected when installing the add-on.
• I couldn't reproduce the issue with other add-ons.

This seems an issue related to an extension that uses the browser.i18n API to localize its options page text (which is what this extension is doing that the other tested extensions were likely not doing).

It looks that the i18n API is failing to retrieve the expected localized strings if the options page is open while the extension is being restarted (which happens automatically every time the private browsing access for that extension is toggled).

The issue is not specific to "toggling the private browsing buttons", e.g. it can also be reproduced by disabling and re-enabling the addon using the related button in the extension details page (which it is also useful to determine if this is a regression or not, because it will allow to verify if the issue was already before Firefox 67, where the extension "private browsing" buttons were not available yet).

:Anca can you test 66 using disable/enable per comment 1?

I can see the content disappearing problem on latest RC 66. In fact, this doesn’t seem to be a regression, using disable/enable addon method I can reproduce the issue way back to Fx 53.0a1 (I wasn't able to install the addon on older builds).

For the record, I reached out to the Evernote team yesterday.

Thank you for the report. We've uploaded a new version today that should address this.

See our latest version 6.13.3 here: https://addons.mozilla.org/en-US/firefox/addon/evernote-web-clipper/versions/