Midi Keyboard Problems
Reported version
3.4
Type
Functional
Frequency
Once
Severity
S3 - Major
Reproducibility
Randomly
Status
needs info
Regression
No
Workaround
No
Project
I have a midi keyboard that I connected to musescore. When I connected the midi and played it was fine, but then randomly the notes inputted would appear on top of each other instead of going to the next beat. This kind of renders the midi input as way more inefficient when it should be kind of easier. 
Comments
You're all but one
Most likely your keyboard is not sending note off messages. Try resetting it, or checking the manual to see if there is a setting you need to enable. MuseScore needs to see the note off in order to know you're not just building a chord.
In reply to Most likely your keyboard is… by Marc Sabatella
i have the same problem. reported it here: https://musescore.org/en/node/303718
for me it only happens in automatic and semiautomatic input node and only if all instruments in the score are transposing instruments
In reply to Most likely your keyboard is… by Marc Sabatella
Here's what I've found....
I run v3.6.2 on both my older win-7 laptop and new win-11 desktop. I have the same problems on the slow host and no problems on the fast host. I ran the free MIDI-OX on my laptop. I do not see any problems with Note On & Off messages, none missing that could trick up Musescore. However, when running Musescore on the slow box, I notice some delayed processing (like delayed, echo of notes on the laptop speaker). This probably means there's significant processing of building the score from the input during note capture. It has even made loud "burping" noises, thrown a very low note into the score, and locked up, where I have to kill MuseScore with the task manager. I generally cannot enter more than 2 bars without a mishap. I include a sample MIDI-OX screen message capture (there are some notes I pressed simultaneously, but there is a Note Off for every Note On).