I have a bike with an 11 speed alfine IGH in the rear wheel. It works fine, and I am comfortable riding it.
When accelerating hard or sprinting for some reason, I've noticed its possible to change at the shifter but the gearbox doesn't react until the chain tension drops for an instant. For the Alfine, this mostly happens when changing to a harder gear.
This is similar but opposite to a derailleur-equipped bike, where changing down to a lower/easier gear (ie chain moves to a bigger rear cog) needs a brief window of lower chain tension to get over. You might have done this when on a climb and have run out of leg in the current gear, and need to change to an easier gear.
Question: Is this bad? Is it causing more wear on the internals of the IGH?
It seems my carefully-cultivated smooth pedal circle doesn't help. A slightly choppier or bouncier pedal stroke allows the gear change to happen mcuh easier.
As a test I managed to ride in second gear while clicking through to about 9th gear, though this was intentional. When riding for real it might be only one gear postion out, but pulling away from a light quickly might cause 3~4 gears difference and when it does catch up I can end up in an overly hard gear,