The premarket activity isn't showing up for 9/22/15; neither is the option to show it/hide it.  Is this is a glitch or has a change been made?  If the latter, I would strongly urge to reverse it, as it's a feature I use every day.

Our RT feed (the one we get from our vendor) is down, which means the RT feed we provide is also down. The issue is being worked on. It will hopefully be resolved shortly.

I still seem to be able to adjust the option to view pre and post market data however.

How to view Pre- and Post-market data
How to view Pre- and Post-market data (v12.4)

the method above is missing on mine, strangely.

any idea on when the RT feed is back online?

I don't have a specific time I can give you at this point. The blank WatchList Columns seem to be back for me and I do have pre and post market data on at least some symbols, but my understanding is that the issue is still be worked on.

It looks like the data should be streaming correctly now. We are in the process of filling in any missing data. Different stream servers are catching up at varying rates however.

The data should now be all caught up and filled in on all stream servers.