I was just informed that the "Clipboard" menu isn't accessible on devices running iOS / iPadOS 15!
StitchBuddy HD is using predefined Apple icons to illustrate menu items since its last major update (version 3.3). Although I was aware that not all icons are available in iOS 15 - leaving some menu items without icons - I didn't realize that the toolbar item for clipboard operations is affected, too. Apologies, and expect a bugfix release on short notice.
You might be able to open the mentioned menu by chance when tapping next to the "Select" toolbar item…