Are backlinks still passed through 301's?

[acee]

In the last few days I've noticed a substantial drop in SERPS accompanied by all external backlinks that arrive via 301 redirects disappearing.

Previously redirected backlinks had been counted by Google.

Only internal and direct backlinks are showing. The redirect pages are within the same domain as the target location.

Are Google updating backlinks or do they no longer count backlinks redirected from pages that have been removed from their index?