FWIW, I haven't had any problems with the brass colored WLP primers in .357M, .44M, 45 Colt. I haven't use a statistically significant amount of them, maybe 500 to 600.
One thought, in this age of narrowing costs (and Winchester is one of the major culprits), maybe Win is using the same metal alloy for LP and LR primer cups. Usually, primer manufacturers use a slightly harder metal for rifle primers because of the harder striking firing pins and higher pressures in rifles. If they have done this, it might account for the failures to ignite.