I tried the same workout last tuesday with similar results. I even skipped my Sunday night weight-lifting session. I had to reduce the target on the last 3 intervals a few percent and was able to complete the intervals at the lower target. Just too much fatigue in the legs to push the watts at the end.
Despite the v02 interval failures, I can definitely feel that my FTP is up from a month ago, so something is working. 240 NP for 5 hours on Saturday was a personal best and I was still feeling strong at the end. I’ve got 2.5 more weeks before my “A” race (stage race) and plan to start cutting volume and doing some local group rides/races as I taper.