Try reducing both the Inter-key and Inter-Device delays. There might be a bug where the 2 delays are swapped and/or added together.

Also check the "How do you select channels..." configuration under:
o Client S/W interface: "Device > Settings > Re-do initial setup for this device (or Advanced setup...)".
o Website interface: "Device > More Options > Redo initial setup for this device (or Advanced setup...)".
It has 4 options (2 numbers, 3 numbers, Number(s) then enter/select, Number(s) only), make sure you selected the correct one.