i don't know if this is your solution, but in my case the solution was very simple:
First, it didn't work in my case, too. After pressing the 'SAVE' button beneath the period parameter, i could also enable the automatic pattern update.
I think, there is no default value for the interval set, so enabling the automatic update must fail !!
I would hope, that this was your problem, too [:)]
sorry but i can't confirm this error.... For further checks i need cat /etc/wfe/conf/up2datedata, the running version and you initial install version (1.811 or 2.000). Thx for your reports and cooperation!