I had a few marks close to the charted one, so I checked on my way back from a dive a while back, but the sounder showed nothing. Upon a thorough investigation into the possible location, considering reports from 1921, it seems to be 4 miles further south. However, as I delve into newspaper reports, the details become increasingly vague. I'm uncertain of its exact location, but this newspaper article offers some clues.
The only ship I could find that comes close to what the Skottier Captain claimed to be searching for was the schooner Peder Wesel, but that dates back to October 1920 and was said to be lost in the East, not the West. This is somewhat nearer to the location of the Ariadne though, a cruiser that was lost during WW1. I couldn't find any other schooners lost in 1921 the Skottier Captain claimed to be looking for.
It's probably going to stay missing this one unless a clue comes to light.
JP has a picture and some information on Flevo 4 on his Facebook Page;