The Keys for the capsules should read ink levels until empty, at which point you replace the capsule OR refill the capsule, then re-insert and it should reset the chip. I would guess that when you took the cartridges out of the printer, they were not reading empty yet, instead they were still showing a 20% remaining ink level, at which point you refilled and put back in the printer. The chips did not reset, because they didn't ready "empty" or "replace ink", so the printer went about it's business until it thought the carts were in fact, empty. This is all based on estimated usage, how big a print and how much of what color ink is being used, the chips don't actually read ink level 100% accurately.
To avoid this problem, the chip resetter does work on these keys and that will make it so you can remove, refill and reset to full whenever you please.
As far as a Key for the R2880, we are very pleased with our current refillable cartridge solution for this printer model, along with the CCPRO ink that supports it, no keys in the near future for the R2880.