[NTG-context] reusableMPgraphic not working

Just working through the Metafun manual and have hit a problem. In the following MWE the green circle appears but the blue one doesn't. Surely reusable graphics must be so commonly used that it has to be me that's doing something wrong? (Context version is: 2020.11.05 23:01) \starttext \startuseMPgraphic{name1} fill fullcircle scaled 100pt withcolor green ; \stopuseMPgraphic Green circle: \useMPgraphic{name1} \startreusableMPgraphic{name2} fill fullcircle scaled 100pt withcolor blue ; \stopreusableMPgraphic Blue circle:\reuseMPgraphic{name2} \stoptext -- Bruce Horrocks Hampshire, UK