I kind of reproduced this, but the problem lies in Intel Quick Sync Video (qsv) and out of our control. It has a maximum for CBR that appears to be dependent on your chip. When you right click the job Quick Sync reports the bitrate mode and rates that it is using. When you supply 100M it exceeds some threshold. On my system, 100M gives “TargetKbps: 34464” and MediaInfo reports 34.5 Mb/s. Interestingly, when I tried with 50M it works, reports “TargetKbps: 50000” in the job log and 50.0 in MediaInfo. 60M also works, but not 70M (TargetKbps: 4464), 80M (TargetKbps: 14464), or 90M (TargetKbsp: 24464)! Thus, it appears to overflow some maximum as the TargetKbps increases linearly along with the overflow. Your chip and its driver give different results. Using ABR does not change the result. So, it appears that bitrate control only works up to a certain level.
If you want something high bitrate then this is your only option and to reduce the quality level to achieve it. Those quality levels are extremely high for video. The default preset uses ~60%, which still gives good quality for x264. Quick Sync and really any hardware encoder is not nearly as good quality as x264. The trade off is speed. Maybe try somewhere around 70%.