Has something changed about after-hours quotes?

I have about fifty stocks/ETFs in my Seeking Alpha portfolio. Until the past few days, about half of them would show pre-market and post-market price changes on any given day. Now, only a handful show such information. I understand that not every stock has enough after-hours volume to show this info, but even my high-volume holdings (such as IVV and IWM) are not showing any after-hours pricing. What's up?