I ended up creating some redundant libraries with :minimal: in the library LSID where BlibBuild usually puts :redundant:. Took me a while to figure out this was the cause of my problems because BlibFilter just crashes in this case. I think it is fine for BlibFilter to fail when a library is not clearly marked as :redundant:, and I have fixed my minimization code to use :redundant:minimal: and :nr:minimal: to be more compatible with BlibBuild and BlibFilter, but it would be nice to have BlibFilter fail a little more gracefully in this case, and just emit an error message that the library must be marked as redundant.

I can vote for this issue too! I'm now generating .blib files and BlibFilter was crashing for me too. I was very glad to find this issue.