I tested now pure vanilla even cba3 not loaded and the issue persists.

Steps to reproduce. I place a vehicle which is viv capable in the editor. Eg. cargo version of Hemmt. Then i place eg. cup c.130 in the editor and drag that with mouse on top of the Hemmt. The icon goes orange as previous, but the audible feedback sound and the text promt informing that loading failed due "no room in vehicle" dont occure as previously happened.

All vehicles. Vanilla and modded.