Graham toshudhiman I just ran a test using the mobile template
I created a page
I added a class (2 actually as the first one still has that bug of no . (dot) )
I added a block and assigned that class to it
I added another class
I edited the block and selected the new class
all worked just fine !
Which block are you adding I was just using a link
Ahh hang on I have found it ok but there is nothing I can do today all the other staff have gone home for the weekend (I am in a different country to them anyway) I will report it and try to find out wtf is going on