Holding the Alt key to temporarily toggle Linked Selection in the edit page doesn't function correctly during playback in Resolve 19 beta 2. Normally, holding Alt allows the user to select individual clips independently of other linked clips (or inverts this behavior if linked selection is toggled off). However, this doesn't seem to work at all while the timeline is playing.
Toggling Linked Selection manually works as expected, even during active playback, but the Alt key modifier seems to do nothing (although it has worked for me once or twice, I haven't been able to find a way to 'trick' it into reproducing this behavior).
I often use this feature to select and disable/delete segments of audio where someone on one audio track might be coughing or otherwise making noise over somebody else, and taking care of it while playing the footage back is super handy and quick.