Embedded Previews keep getting replaced

[Nvertd]

I have import preview setting "Embedded and Sidecar"
Generate standard previews while cpu idle turned off
LRC still randomly starts generating standard previews while I am culling images.

[JohanElzenga]

Do you apply a preset on import, or have a preset as camera default? If a preset applies things like a different profile, then I think it is expected behavior for Lightroom to generate standard size previews to show this change, and not wait until idle time.