Downloaded a trial of Lightroom yesterday. Not able to import any images, I've tried to add raw files and raw/jpeg, getting a message "the files were not recognized by the raw format support". Also received a message, "could not read preview ". Using a 2010 Mac with the Catalina operating system.
Incompatibilities between Lightroom 5 and Catalina do indeed exist and will never be resolved because Lightroom 5 is no longer supported. If you use legacy software like that, then be careful upgrading your system software.