Hello David,
at this moment I'm not able to say where exactly is the problem (will forward to the team), but for now the workaround should be by opening the "board\clock_config.c" file and in the YAML code (lines around 40-50) there is line with "package_id".
Please change this line to the correct package like this:
package_id: LPC804M101JDH24
If you did not do any changes in the configuration, delete the <projectname>.mex file inside the root of the eclipse project.
After that open the tools again.
Regards,
Libor