I have setup a template with group aggregate functions to monitor the health of the whole group. I have dummy hosts for each group and define GROUP_NAME as a user macro.
For example I have one item of type Zabbix aggregate:

grpsum[{$GROUP_NAME},"system.cpu.util[,idle]","last","0"]

Everything works when theres no spaces in the user macro e.g. GROUP_NAME=Linux_Servers

However when the Hostgroup and accordingly the macro is written with spaces it doesn't work e.g. GROUP_NAME=Linux Servers

This is inconvenient as I have to adjust my naming scheme for Host groups to overcome this.