While sequencer is playing, punching steps in is buggy

[BoogieMonsta]

While sequencer is playing, punching steps in only works if done very slowly.

Otherwise, the loop plays the steps in unpredictable spots of the sequence. When that happens, stopping and starting playback fixes the issue, the sequence itself is not where the bug resides.

Punching in steps while the sequencer is playing also generates clicks and pops, potentially linked to issue #4.