Reported by User:Zitraum at https://www.mediawiki.org/wiki/Topic:Un0aidtdl7xgwbzc
Steps to reproduce:
# Enable two buttons for editing.
# Go to https://en.wikipedia.org/wiki/User:Whatamidoing_(WMF)/sandbox?useskin=minerva
* Note that this is not the mobile site.
# Click the "Edit" (not the "Edit source") button.
There are two related issues:
# If you previously used the mobile visual editor on the mobile site, neither editor will open.
* → https://gerrit.wikimedia.org/r/470084
# After opening wikitext editor, dropdown to switch to visual editor does not work.
* Solution: the mobile visual editor doesn't load on desktop for complicated reasons, ditch it and instead let the desktop editor load
* → https://gerrit.wikimedia.org/r/470087
Also, @Deskana found a (probably) separate problem that suggested that the Edit buttons simply didn't work after making one edit. (??? needs clarification)