Middle doesn't seem to work with RealVNC

[pdbj]

Middle click just pastes 6, not the clipboard contents.

[rxhanson]

Thanks for reporting. It's up to RealVNC on how to interpret the middle click produced by the app. For click gestures, Middle will modify the click to change it from a left click to a middle click, while the tap gestures will generate a middle click programmatically. Sometimes virtualization apps will treat those differently. Does a mouse with a physical button work differently in RealVNC for you? Either way, it is likely that the best solution is for RealVNC to properly handle programmatic or modified mouse clicks in macOS.

[pdbj]

Thanks for the hints; I'll report back when I can try a physical 3-button mouse.