Our engineers were able to pinpoint the problem. Your screenshot was very helpful. Thank you.
We duplicated your problem with a test account. It is caused by certain unsupported characters in the username and/or password. For now, please change your password to only include: alpha numeric characters and characters like: $, !, @, #, %, &, *, ?.
We will fix the problem ASAP. It seems to only affect this Mac version software. We will release a new version in the next few days.