Insert Fastener Lack of Length Options

[s.mckenzie.fugro]

I am revising an assembly that I created last year, but I am removing all the fixings from the McMaster-Carr catalogue & using the Insert Fastener command & which has been working well so far, apart from one fixing which does not provide the required length, unlike the McMaster-Carr catalogue. Why is this the case, as this is very frustrating.