Its G-TOYM in the DB
Yes, but it's not quite as simple as that.
I'm sure that it is indeed G-TOYM in the Updater's database, but it's G-OHAJ in the database that currently ships with RadarBox 3.13 and 3D, so that's what appears on the screen - hence the OP's query.
And no amount of double-clicking on the Mode S code in MyFlights will get it to populate correctly. The only way to do that is to manually update it (as Dave has now done), or to delete the G-OHAJ record - which of course presumes that the user knows it's wrong in the first place ...
A bit of a Catch-22 in fact, hence the OP's understandable confusion.
We urgently need an architecture where updates from the master database propagate to users' RadarBoxes without requiring them to have psychic powers :-)