I thought I'd further explore the Live Loops feature in Logic, so I recorded some guitar, selected a region to loop and copied that part of the region to a Live Loop cell, which worked as expected.
Then I decided I wanted a different guitar sound, so I selected a few from the Library and weirdness ensued -- as shown in the video, with each newly selected patch on track 1, the cycle length changes. Some patches remove the waveform display but you still hear it. This is on 10.8.1 on Sonoma 14.2.1. On 10.7.9 the loop length doesn't change but the disappearing waveform still happens in certain patches.
Changing patches of a running loop doesn't seem to be a problem with software instruments. Is this a known issue I've overlooked?