I've found a issue when using the grouping feature startcollapsed. (If not startcollapsed it works well).
It works as expected but once trying to uncollapse a group it required 2 attempts. First click does not get recognized, required a second click to uncollapse.
Was this the intended functionality? I expect this is a bug using the startcollapsed only time I have seen it required 2 click initially to un/collapse a group. The store being used for rows is already loaded.
I ran into this issue through Bryntum Gantt chart as from their Developer mentioned that it happens on Sencha Grouping Example.