Crossing staves notation issues

Hi, gang!!!

I use MuseScore 3.0.1 portable version with UbuntuStudio 18.04.1 LTS.

I had an score with this layout:

https://musescore.org/sites/musescore.org/files/2019-01/Captura%20de%20…

I wanted to put the first note of the triplets into the F key (using [Control]+[Shift]+[Down Arrow]) and I got this:

https://musescore.org/sites/musescore.org/files/2019-01/Captura%20de%20…

Well, there are two issues here (I don't know if it is because I did something wrong, or...):

1) The triplet indicator numbers were put two far of the triplets position.

2) The whole note silent was not removed.

Can somebody teach me how to fix (and avoid) this???

Blessings and Greetings from Chile!!!

JUAN