as many of you know the Lockdown extension is not very well interacting
with MediaWiki and other extensions since MediaWiki 1.27. Several bugs
were reported and some of them were already fixed to make this extension
work somehow. Many thanks to all people involved!
The current big issue appears to be that API interaction is broken due
to some bad caching of user groups as described here:  in this
comment  and in this attempted  fix which is currently stuck.
Perhaps there is even another issue, perhaps all of the observations are
unrelated to each other and consitute seperate issues to the problem. I
am not sure.
Since this is one of the most popular extensions (top 15 according to
the extension distributor and top 50 on WikiApiary) ... Perhaps there is
somebody out there who may be able to fix this issue for the extension's