But .... You are ignoring the fact that the spade connection on the fuse is a mechanical connection and is .... part of the fuse body. A bad connection on that spade could easily get hot enough to glow and melt down that fuse holder.
Not trying to say that absolutely was the cause, but you seem to be determined to say it isn't a possibility at all. I have seen similar things happen many many times.
.... and you are trying to belittle anyone who could possibly think that could happen.
<sigh> You still are not reading what I wrote. I acknowledged multiple times that a bad connection can get hot and glow. I also said that IF that bad connection was on the end of a fuse, that the transferred heat from that connection could possibly also cause the fuse to glow. However, I also said that a bad connection at point A would not cause a fuse located somewhere else (point B) to glow. Not sure why that is so hard to understand.
I am not trying to belittle anyone. I am simply voicing my opinion (based on decades of electrical experience). But whatever, I'm not going to continue to argue about it. Hope the OP'er solves the problem, whatever it was that caused it.