Failure From Fatigue? How Do I Continue? Cat 4 Questions! Episode #423

I have just failed a workout due to (I think) fatigue, and I am unsure how to continue in my plan. I have just started a new base block, and figured Id give high volume a try. I have some extra time nowadays and figured I would use it. The first week went well. I felt super tired after my sunday workout, and took monday off (some light yoga). Today (Tuesday) comes around and I’m still feeling tired. I put the workout off as long as I can, but get on the bike nonetheless. Sweet Spot is on the menu. I get the first block done, but muscles just werent there today. Mid block 2, my brain convinces me I need to rest. My question is, how should I continue? My proposed solution is to cut out all of the extra mileage I did last week and try to do barebones high volume plan (I added just under 2 hrs of free riding to the first week because I was feeling really good after a couple of free weeks). Another solution, one that I would like to not resort to but I will if need be, is to do mid volume and add endurance as I feel that I can. My background. 26yo, 5’11" (180cm), 155lbs (70kg), 229ftp. Started structure in Feb after not riding for a long time. Did Sweet Spot base. Trying to do yoga/core 1x weekly, and do more running as I am terrible at it.