For me, at least, this has never worked but does now.  Great!
 
[log in to unmask] just now got a warning about disk 300.  Here is the
line from my local sysvars that just started working.
 
...
* MDISK.cuu = 'acc rw ro nl th1 th2 / wlist / wmsg'
MDISK.300 =   '*   N  W  W  95  100 / [log in to unmask] / Public Notebooks'
...