I was digging into this issue and I found that I broke this functionality on the latest release (v1.6.1), due to I made the arguments passed in each command case insensitive. This broke the value for timezones when try to compare the entered value with the valid values, this comparation is still case sensitive. And that's why still works if you enter the value manually when it's asked.
Thanks again for reporting this issue and will be fixed in the next release.