The early evening races in DRS were massively affected, one person we spoke to on Discord said there were only three in her pen when there'd usually be over 20. She assumes the race will be nullified, but is gutted because she won it by 7 minutes, having soloed it, dropping the other two riders in the first 2km.
Our race at 19:30 seemed to be at the tail end of the problem but it still caused issues. A number of riders (myself included) had the Join Now button and clicking it transported me to the correct session (e.g. all free riders disappeared, only names of those I was racing against were in the Zwifters Nearby box) but didn't take me to the actual pens. Half of my team-mates were on the Watopia Pier, the rest of us were still in various spots on the road along the shore front. Most got it sorted by quitting the race, quitting the app, or at the most extreme rebooting the computer before rejoining, but for me even after doing all of those I still couldn't get into the pen. Gave it one final try with a minute or so to go and it got stuck on the blue "Going to Watopia" screen while I could hear the countdown hit 0:00 on Discord. When eventually it came back, I was finally in the pen but all the other riders were 35 seconds up the road leaving me in 18th (and last) place and having to chase back on.
However I still went for it and PR'd the Hilly KOM and Radio Tower, plus a 2nd best time on the Epic KOM and finished in 8th place overall, with a 3rd place FTS on the Radio Tower to boot.
No video footage unfortunately as I was so stressed in trying to get into the race that I never started the recording, but I can show you one of my team-mates' Twitch video, though you only see me in brief spots on the Epic, then finally overtaking him on the Radio Tower.
View: https://www.twitch.tv/videos/2906100158?t=0h10m0s