Merge on mac not working?

I cannot have merge on mac working. I can on ios. i did read the manual . any ideas ? I tried 5, then just two notes . right click pop th emarge, but nothing happens then . anybody more lucky ?

using 19.1.4

Quit and restart the app.

I’ve been tracking this issue. Seems to come up after the app has been running for a while. Should have a permanent fix soon, but restarting the app will restore the functionality.