Can't edit or view translations when "Account administration pages language setting" is active

When I enable "Account administration pages language setting" on admin/config/regional/language/detection and choose a language on my user profile, I can't edit or view translations but only the node in the source language.

Steps to reproduce:

• Create a Drupal site, enable the relevant language and translation modules.
• Choose or add languages, here: Spanish (default), English, German.
• Enable the translation for a content type, e.g. Basic page.
• Enable the following detection methods: Account administration pages, URL (Path prefix).
• Choose English as "Administration pages language" on your user profile.
• Create a node in Spanish.
• Add an English and a German translation.

So far all fine! Continue as following:

• Visit the source node, hit the Translate tab to edit one of the translations.
• On example.com/es/node/1/translations choose the English (or German) translation, and click Edit.

Unwanted result: You see the (correct) URL example.com/en/node/1/edit, however you are not editing the translation but the source node, the page title is something like "Edit Basic page XYZ".

Expected behaviour: You edit the translation. (In this case the page title would be "Edit Basic page XYZ [English translation]").

When I try to view the English translation going to the source node and using the Language switcher block, I'm confronted with the same problem: The URL that I get seems correct (example.com/en/node/1), but I stay on the Spanish content.

Steps to avoid the problem:

• Disable the detection method Account administration pages, OR
• Select No preference as Administration pages language on your user profile.

In my opinion, the issue is very critical for admin users or editors who don't understand the default language of a site. Thus, I couldn't believe that I didn't find a relevant bug report in the issue queue. Did I miss something?