Steps to reproduce:
- Make a new score
- Create two players, a pitched one (e.g. vibraphone) and an unpitched one (e. g. claves)
- write some notes on both staves
- put some playing techniques on both staves
- in the first staff (the one containing the pitched instrument), select two adjacent playing techniques, right-click>Playing Techniques>Group Playing techniques. Result is expected: an arrow is created between the two techniques.
- in the other staff, do the same. Expectation: an arrow is created. Reality: nothing is created.