Missed Roth Catch-up contributions

[30Rock]

Due to the new Roth catch-up mandate, we have a couple plans with situations where the Roth indicator did not get turned on properly to allow the deemed Roth spillover. This is some new territory for me!  I am checking on corrections - 1. any QNEC will be pre-tax for missed Roth, 2. if the missed contribution occurred more than 3 months ago then a 25% QNEC will be due based on missed deferrals during the applicable period of the year. How is this correction feasible under the Roth catch up mandate? It does not make sense that their catch ups will be a pre tax QNEC.  Any thoughts would be appreciated.