If in the exp conf you try to disable the channel that is also the global timer an exception is raising.

A patch is required in sardana/taurus/qt/qtgui/extra_sardana/expdescription.py  (Line 534)

mgconfs = conf.get('MntGrpConfigs', {})
for mgname in self._dirtyMntGrps:
    mgconf = mgconfs[mgname]
    mgconf.pop('timer', None)
    mgconf.pop('monitor', None)