Why does my chain have a single hollow pin?
Its not a master link - that's probably the one-use pin that was used to close the chain the first time.

This is what a Shimano pin looks like after its been snapped off.   There's a clear difference to show this pin should not be pushed out again because the plate holes will be enlarged slightly.



Your one doesn't look quite the same - it does look like a snapped off line exists though.  This was probably a hollow connection pin rather than the solid one supplied with that chain, or perhaps sunrace pins are all hollow.