The problem is solved. Thanks to Glock
@Mr_GLCCK , Nith
@Probot_nith , and Sundar
@WILD_PLANET_ART for your help. The solution was to log in to
arenatrade.io via MetaMask and sell it there. The sale via Arena on
Arenatrade.io failed at the final step because the approval prompt via MM did not appear. Also, there must be sufficient
$AVAX in the wallet (🎩 to Glock) ; 0.16 AVAX wasn't enough to even unlock the sell button...