I can say in the decades that I have been a Shoah researcher, I have never come across anything like the case of Hartog Cohen.
According to Yad Vashem, Hitler himself ordered Hartog Cohen and his family to be protected at all costs.
By this point in his life, Hartog had become quite well-known in art restoration circles. The Reich had stolen a lot of art, and a lot of that art was damaged during the heists.
There was allegedly days worth of arguing leading up to the 18 January 1944 transport from Westerbork to Theresienstadt about what to do with Hartog Cohen. Westerbork was given permission to deport Hartog to Theresienstad, but only if they sent four unnamed paintings along with him. Staff at Theresienstadt were also ordered to make space for him to open a workshop in which he would be able to restore these paintings undisturbed; it is presumed that the Reich would send more art to Theresienstadt over time for Hartog to restore.
Hitler himself said that he would relax his policy of murdering every Jew in the Netherlands specifically to exclude Hartog Cohen and his family (as well as the other art restorer at Westerbork, Lion Morpurgo).
Hartog lived in Theresienstadt from his deportation on 18 January 1944 to liberation. He spent his entire imprisonment restoring artwork.