I did hammer the bk-2c-b, I think 2-3g of it over 6 weeks, had a gram of mushrooms too, and a little 5-meo-dalt, tripping multiple times a week for 6 weeks & my last trip on bk-2c-b ended after a few hours when it should last 12+, probably that. I had over a week off any psychedelics except weed (cut down on that too), think it was a week last Monday my last go. I have experienced similar false starts with other drugs in the past, so I'm not against trying it again at some better time.
The physical effects did feel pretty strong for one tab & seemed consistent with taking a really good tab of LSD, just shorter lasting & no 'trip', resting pulse went up to 160 at the start, came back down again, if I'd had 2 it would've been more unpleasant, so I'll try less next time, I don't think it was not taking enough & there was clearly some drug on the tab. I'm pretty light, I think one should be enough for me with no tolerance. Felt more like cross tolerance than some kind of allergy, the physical effects were consistent with my past LSD trips, just no euphoria or psychedelic effects.
That sounds like pretty much exactly what happens to me if I've been tripping too often. Basically, the less comfortable aspects of tripping are more over-powering than the pleasant aspects of tripping. Not only do I trip less hard, but I feel an increased sense of body-load & physicality. Given your regime with the bk-2c-b & 5-meo-dalt, there's no way a week is a long enough break. Even when you reset your tolerance you may still find a single tab underwhelming. Keep another half at hand, you might be surprised how much it will increase the trip. I've not had two tabs at one go yet, so I'm wary about recomending that dose, but plenty people do higher doses & get on fine with it. 1.5 tabs is definitely quite a bit more visual than a single tab!