On the top of my guess list: it was updated to King 2.50 (R30 version ROM) before you bought it.

I don't know if there even is an official R40 version ROM of King 2.50. I only know of R40 King 2.20.
Photo on the wiki of R40 2.20: https://www.schach-computer.info/wik...=Datei:R40.jpg
Photo of R40 with the Gideon ROMs: https://www.schach-computer.info/wik...TASC_R40-6.JPG note that it says R30.