Not at all unlikely. That is one of the loneliest pieces of a very large ocean. A lot of the recognizable stuff will sink, and the stuff that floats will spend months being broken down by seawater or having stuff grow on it. Eventually it will wash up on a beach where it will be cleaned up with the literal tons of trash that wash up on any beach these days. Or will not be cleaned up because it is a place where humans don’t go.
If you think of a pristine beach its pristine because it gets cleaned up regularly. Any ocean facing beach these days accumulates so much trash. I used to do beach cleanup surveys on windward coasts, and we would regularly find stuff that could have belonged to an airplane (carbon fiber, composite honeycomb, etc.) it was almost never worth investigating since there was almost no way to know how long it had been in that beach and how long it had been floating in the currents before that. This was in the Caribbean, so I mostly assumed that all that stuff was related to drug smuggling planes. The only time we ever got a call back about something we found on the beach is when we found a drift buoy from NOAA.
This is the long way of saying that it surprises me not a bit that nothing much was found. It’s more surprising that anything at all was found