I never seem to see any references anymore to Barnard's Star, 61 Cygni, and the other twenty or so "known" other systems prior to the explosion of discoveries since the '90s. Have they all been invalidated?

Only Gamma Cephei b turned out to be real. It was detected in the 1980's, but the scientists thought it more likely that the signal was from stellar variability than from a planetary companion. The rest of them were attributed to instrumental errors. For specific example, the planets at Barnard's Star were said to have been detected astrometrically, but it turns out that the orbital periods oddly coincided with the time inbetween telescope maintenance.

More recently, HST observations, and radial velocity observations has verified that those "Classic" extrasolar planets do not exist.