The bracketing makes it look like this hasn’t come through “as” a piano – so you might want to check in Setup mode what instrument(s) this is currently set up as.
If it’s not one piano, and instead perhaps two separate instruments, you might want to add a piano player and move or copy the music across to the new piano player.
Also in bar 2 some notes in the LH staff belong in RH. You can select them and move them to the staff above with Alt-N – Then the B octave in LH will appear as a whole note again automatically. And where notes are the wrong length (bar 2 downbeat, bar 3 beat 3) you can select them and change them to the right length without affecting the following notes.
(On inspection, this is obviously the “Moonlight” Sonata. For such straightforward music it may actually be less work to recopy it than wrestle with midi import.)