On https://beta.wikiversity.org/wiki/Main_Page?useskin=vector the first click on ULS does nothing. The second click works as expected.
Old report (resolved):
With $wgULSPosition left to the default value of personal:
On load:
After clicking once, the icon changes size, but the overlay doesn't load:
The second click does nothing, and only on the third click does the language selector appear.
Most WMF wikis have $wgULSPosition set to interlanguage where it isn't broken, but some don't:
'wmgULSPosition' => [ 'default' => 'interlanguage', 'special' => 'personal', 'wikimedia' => 'personal', 'betawikiversity' => 'personal', ]