A no-bail hold with a clean appearance record and a paid attorney in place is unusual enough that something specific had to drive it, and finding out what that is should be the immediate priority.
The most common explanation is that the prosecutor presented the court with something compelling enough to convince the magistrate that release posed a risk beyond just flight. That could be new evidence that surfaced, an affidavit from a witness or law enforcement, information about the nature of the alleged offense, or a theory about danger to the community or potential tampering with witnesses or evidence. Magistrates can issue no-bail holds when the argument in front of them is strong enough, regardless of prior appearance history.
A clean FTA record and consistent court appearances are strong factors in favor of bail, but they do not override everything. If the charge itself is serious enough, or if the prosecution presented credible information suggesting release creates a specific risk, the magistrate has the authority to hold without bail.
The attorney is the first call. If everything you are describing is accurate and there was no warning this was coming, the attorney needs to explain exactly what happened in that hearing and what the prosecution put in front of the judge. That information shapes everything that comes next, including whether a bail reconsideration motion is worth filing and on what grounds.
If the attorney cannot give a clear and satisfactory explanation, a second opinion from another criminal defense attorney is worth pursuing. Something significant happened in that courtroom and you deserve a straight answer about what it was.