If you save a quick A/B preset while playing / rendering, it can produce _recordable_ crackles. But saving it should not affect sound at all.
Steps to reproduce:
- Load a song with quite cpu load, put melda mrecorder in last master slot
- Put a plugin before mrecorder, for example a limiter which introduces PDC / latency
- Record the song, quick save a preset of the limiter. If you don't hear a crackle, try other plugin
- Stop record. Check the recording, it has the crackle recorded.