Thanks, now I think I understand, in fact I had exactly the same problem:
The problem, as you see, is that you’ve increased the limits of the main deck, but subdeck1 is still applying its limit. Yes, I also find this behavior a little bit counterintuitive.
Anyway, does this explain the issue?
Ps: as a workaround, increasing the new cards a day (today only) from subdeck1 to 4, should work as you expect.