When importing my own animated hotspot icon (APNG) into the library, I get the message "Format or compression not supported." What am I doing wrong?

This may have to do with the settings of your .apng file export. If you use a program such as APNG Assembler, the options "Optimize palette" and "Optimize color type" may be selected by default in the compression settings. Deselect the option "Optimize Color Type" for 3Dvista to be able to recognize the compression type of the file.