Has anyone experienced issues booking some UA awards with A3 miles? Keep getting error message abou not enough miles (required 12,500 and I have more than required in my account).

Yes, 12,700 miles and it's not linked.

Called today their US number and got connected to a very nice agent in a matter of seconds. After few minutes on the phone checking the issue, she said my itinirerary was pricing as return for some reason, thus 25,000 miles instead of 12,500. She placed my reservation on hold and promised to call me back tomorrow with details. She also mentioned her full name like 3 times and made sure I took a note of it asking me to call should I have any more questions:) In contrast to SAS, where agents are mostly acting as if they are doing you a favor (even if you are flying in business), A3 seems to be highly polite at all times (and I don't even have status with them). Will update tomorrow.