Although holbein's portraits contained visual detail, what were they often lacking?

His portraits are sometimes considered distant and cold, offering little insight into the character, feelings, or personality of his subjects.

Holbein's portraits contained visual detail  and they were often lacking expression or emotion.

Explanation:

Holbein was said to be one of the greatest portraitists from the 16th century. He had an exquisite  management and attention to detail that resulted in almost realistic portraits in the Renaissance Humanism era.

He had a "Mannerist" like concentration on textures, surfaces and details that made his work extremely realistic for the time. He worked with religious themes, humanists circles, portraying important humanists like Desiderius Erasmus, but one of his best work is the portrait of Thomas More. He illustrated books as well. He was a known printmaker and is, now days, recognized for his contribution in book design. He has also worked and gained reputation working for the court.

He had a unique style as he was extremely precise. As mentioned before, although his portraits contains extremely well defined visual detail, some say they lack of expression and emotion. Maybe this obsession to detail is what relegates his interest in making more expressionistic or emotional portraits.

The characters portrayed are shown almost as statues unable to express any emotion. I've read somewhere that this characteristic is believed to have deeper meaning as it also talks to us about the painters personality. It  was said that his art lacked of spiritual involvement as most of the art those days had. He  was known to be a very reserved and detached person, not much people had enough confidence or trust to actually say they knew the painter in depth. So I believe this distant characteristic his portraits have relate closely to Holbein cold personality.