Different midi notes automatically selected when click on one note

Hello
A very weird behavior appeared in cubase 15.
I just create a midi event and if I put 3 notes starting at the same time, they are like linked.
If I click on one note, all the other notes are selected automaticaly.
It also happens when the clicked note length is long, in this case all other notes inside the range of the length will be selected.
Because of that, it is just not possible to use the editor as I cannot adjust note as I want.
Luckily, this is not happening on my old project so I have to start from old project.
Do you know if there is a parameter about this behavior I could change to have only one note selected ?
Thank you

In the Key editor
NB: Mac OS M1

If I click on C3, all the other notes are selected :frowning:

Hi,

can you attach a screenshot, please?
We would need more details - what exactly are you doing? Are you working in the key editor or the In-Place-Editor? Which OS are you on?

It is difficult to take a wild guess based on the info you provided :wink: