Failure to Extract

[VASCAR2]

Sounds like the faulty bolt extractor was loosing the grip on the rim of the case. I’d try an O ring on the extractor spring on the troublesome bolt. You could also just swap the good bolt’s extractor spring and O ring into the troublesome bolt to test. I’d also compare the two extractors and make sure the troublesome bolts extractor had no sharp edges digging into the rim which can cause the spent case to hang on the extractor and not get ejected cleanly.