When I first visit the "Social networks" report, it does not show the names and icons of the networks:
If I change any settings using the hidden gear icon, for instance by switching to hierarchical mode and back, then the names and icons appear:
It is not a specific value of the settings that causes the problem - the problem happens regardless of what the original settings were, and it goes away on any change in settings, even changing back to where they began. Changing the date range causes it to reset; the names disappear.
Clicking on "Row evolution" for a network with its name missing produces a pop-up with the error "Error: Expected label to be an array, got instead: " (nothing visible after the colon). Row evolution works normally after a settings change causes the network names to appear.
The problem seems specific to the "Social networks" page; I haven't seen something similar on other pages, though there may be some that I haven't had occasion to visit.
It has existed for at least a few months; I kept hoping that the next Matomo upgrade would fix it, but so far no such luck.
Thanks for the report @mskala - so far we haven't heard or seen this bug in Matomo. Are you using any browser extension, do you get the same issue across different browsers and devices?
Symptoms are the same in Firefox and Pale Moon under Linux, and in Internet Explorer under Windows 10. My Firefox has AdBlocker Ultimate and NoScript but my Matomo installation is supposed to be whitelisted in both of them; and the other two browsers are unextended.