Doing Heroic Strikes, I ended up on Io for the new strike, The Festering Core. Me and two Titans started out as normal, killing Vex and starting to unlock the gate, I noticed something off—there was no Darkness zone where there should have been. At first, I thought there was a specific plate activation that triggered it, but nothing happened and we were allowed to go as planned. The strike kept going, and still no darkness zone! Not that I was complaining, because my teammates were dying left and right. We get to the end, I figure--it's GOTTA come on for the boss fight, right?

No boss.

Just an empty room filled with Taken blights and wall Phalanxes. Dunno what happened, what we did or didn't do--but we ended up stuck in the boss room with no boss(and obviously no way out). We all had to quit.

Did we stumble upon a rare occurrence or is this a known issue?

A really annoying one at that. Not sure if it's been commented on by Bungie proper, but it's well documented in reddit and the Bungie forums.

It happened again, on The Insight Terminus! There was a barrier, which is normal when waiting for someone to land, but then it disappeared and no enemies spawned. We made it all the way to Kargen's first appearance before some enemies showed up in the teleporter. We killed them and opened the gate, but they just kept coming--a lot more than normal. Eventually, we walked in and went through the loading zone, only to come across another barrier, this time in the Radiolarian fluid. Arc burn was on, so we obviously couldn't just sit there. We ended up having to wipe(luckily the Darkness Zones triggered like normal).

This doesn't make any sense. I've never seen stuff like this until VERY recently.