Why does the FMC in B737 limit the climb speed to 230 knots on the VNAV mode until the leading edge devices are fully retracted?
The non normal checklist QRH will answer your question.  If the LE flap transit light remains illuminated I.e the leading edge flaps and slats haven’t retracted or disagree with the flap handle position, then the QRH directs you to limit the speed to  230 kits until you have rectified the issue.  VNAV is honouring that restriction.

Hope that answers your question.