Hi jannpls,
yes, as already mentioned by MikeS, if you have connected a Sustain Pedal (e.g. Yamaha FC5 or FC4A) to the SUSTAIN jack of the E463, make sure that the Pedal is connected before switching on the instrument and do not (accidentally) press the Pedal before the instrument is has started completely. (Otherwise the Pedal will work "reversed".)
If this is not the error, the parameter "Release Time" could be set wrong (too high): When the function combination "4" is assigned to the Live Control knobs, the knob "B" controls the "Release Time" for both Main Voice and Dual Voice. (See pages 25 and 57 of the E463 Owner's Manual.)
Check also the Function parameters "017 M. Release" (= Release Time of the Main Voice) and "027 D. Release" (= Release Time of the Dual Voice). The default value is 064 here. This determines how fast the volume of the voice falls to 0 after the key is released: The larger the value, the longer the sustain. The smaller the value, the shorter the sustain. (See page 67 of the Manual.)
Hope this helps!
Best regards,
Chris