There's a "Smolov experience thread" in this forum. Lots of great information and a whole bunch of posters ran it through with great results and provided a lot of insight.
The intense cycle is absolutely brutal. I'd give it one more shot and if still absolutely unable to complete the reps for that day, drop each day by 10-15 pounds. You may just have had an off day as others mentioned, and there's also a chance that your body just needs a couple sessions of squatting at 90%+ again to get back to where you were before the switching.
In the future, be sure to work in the squat negatives at 5-10% above your squat PR during the two switching weeks. For a lot of people (myself included), going 15 days without a heavy weight on your back will make the squats during the first week of the intense mesocycle feel insanely heavy.
Finally, don't be afraid to increase your rest time between working sets, or even take 5-10 seconds between reps. So much of Smolov is having the right mental state. When you get under that bar you need to be 100% confident that you're ready to nail it.